To the original poster - I happened to browse briefly through this thread a little earlier today when it wasn't convenient for me to type an answer, but now that I have time I am going to briefly write up what occurred to me as I read earlier. My apologies if I have overlooked some details from your original post and/or those of others.
First of all, I think you deserve kudos in addition to sympathy. You mention that you and your wife are both "religious" and that shows by the desire and willingness of both of you to remain committed to preserving and enjoying this marriage and each other's sexuality in those ways which are still open to you. I know this isn't the place for religious comments but I hope it is OK for me to tell you that I personally believe that God is going to bless you for your obviously steadfast faith and commitment to Him and to each other despite what has befallen you. You and your wife are both very lucky that God has brought the two of you together for each other. And specifically in your case I would like to add that being a man has spiritual and mental as well as physical components. You may be one of only a very small percentage of men to have lost a few inches of flesh physically, but I think you are one of an even much smaller percentage of men who would have shown the godliness you have in your acceptance of the situation. That, in my eyes and I'm sure God's, makes you far more of a man than most men who still have their penis.
You have stated as presumably accepted (on your part) fact that orgasm is no longer a possibility for you either now or in the future. And as I am not a doctor and am in no way qualified to pass judgement on the accuracy of that statement in your situation, I am in no way going to attempt to argue with anything that you based on your discussions with your medical professionals have come to know and understand for yourself. Nonetheless, you did ask if anyone knew of anything or had any ideas, so on that basis I am going to comment.
As stated I'm not a doctor. But I have had extensive training in human anatomy and physiology and I do know a few basic facts:
1) The pathway for penile sensation does start in the penis, but the nerve pathway continues from the penis all the way to the spinal cord and ultimately the brain. It is my understanding that THEORETICALLY it is possible or perhaps even likely that the experiences of ejaculation and/or orgasm could still be triggered in you through stimulation of some part of that neural pathway. The question is, is there a method by which it can be done feasibly and safely. That is what I do not know because even if I had the medical qualifications I would not be able to make a statement because I do not know the specifics of your situation like your doctors do.
2) Orgasm and ejaculation are two separate biological functions and depending on your remaining neural wiring may or may not be able to be brought about "together."
3) Unless a doctor has specifically told you the sorts of things I am about to suggest are not applicable and/or have no hope of working in your situation, if I were you I would be sure to ask about and investigate the possibility of any of the following. I do understand that you are not asking about ways to reconstruct a functioning penis or have intercourse - you have accepted your limitations in that area and in fact already found workarounds. You are specifically asking for way(s) in which to deal with ongoing normal sexual desire and physical need for "relief" as you have found no such means yet.
4) As others have mentioned, vibrators or similar devices applied to certain areas of the body might provide nerve stimulation sufficient to bring about the effects you desire. Also, although I have never heard of whether it is done for situations such as yours, I do know that there are nerve stimulator devices which are applied to the spinal column itself, with the purpose normally being to block/cancel out chronic pain from back & spine problems. Because as I said the nerve pathway is penis-spine-brain, perhaps the use of a device, whether a "toy" like a vibrator or something implantable, could provide you with a means of experiencing ejaculation and/or orgasm again. If I were you and I had not already done so, I would ask for a referral to a neurologist and/or neurosurgeon to discuss possibilities. Certainly you should do this as soon as possible in case the options are in any way limited after the upcoming implementation of the Affordable Care Act ("Obamacare"). Of course, your options may also be limited by any ongoing treatments you may be receiving for your cancer.
5) If you continue to be plagued by unrelievable sexual tension, you should discuss with your doctor the possibility of treatment aimed at decreasing your libido and/or somehow dealing with that tension. For example, while it is unlikely any doctor is going to be willing to recommend let alone go through with a physical castration operation for you, perhaps a "chemical castration" might be considered to deal with your libido. And again I am not a doctor but a thought that would run through my mind and that I would ask my doctor about if it were me is --- well, I know that male hormones are implicated in increasing the chances of cancer or increasing the aggressiveness of existing cancer - perhaps even increasing the odds of a recurrence of treated cancer. Your male hormones at the very least put you at increased risk of prostate cancer, perhaps more so since you have already had penile cancer. So perhaps a chemical treatment aimed at reducing those male hormones might have additional benefit for you as far as reducing those risks as well. Nonetheless this is not something to be pursued lightly, because a lack of male hormones could also have other undesired affects such as loss of muscle mass and strength, general fatigue, etc. But this whole area is a reasonable question to ask your doctor.
6. Finally, whatever you do as far as dealing with your own need for help with your sexual tension, do continue to consider the use of other "toys" as an aid in helping with your ongoing relationship with your wife. As just one example, devices such as "strap-ons" while not doing anything for your physical pleasure might not only provide a way of bringing pleasure to your wife but might also give you some enhanced mental esteem and pleasure in enhancing a feeling of "being one flesh" with your wife.
Once again, I commend you - and am humbled - by the strength you have shown in dealing with your situation.