Injections work differently after my prostatectomy

[graymare]

I used to be a regular reader/contributor here when "all" I suffered from was ED. Trimix was a godsend giving me erections that wouldn't disappear at the wrong moment. What I never realized was that back then, during intercourse, sexual stimulation was helping engorge me further, making my erections even better. And that led to great orgasms and ejaculations.
Fast forward a few years and now a lot has changed. I had a radical prostatectomy 30 months ago. Yes, the cancer is gone, but so are the nerves that let me get any form of erection, no matter how weak it might have been. I am one of those unlucky guys whose doctor thought he spared the nerves during the surgery, only to find out they never would heal again. You would think that since I had used Trimix before the surgery, I should have had no problem transitioning to post-prostatectomy sex. Not so fast. Not only did my surgery led to impotence; it also led to climacturia
(urinary incontinence during ejaculation). I found this out from masturbating. My wife would have nothing to do with that so intercourse was put on hold until I became continent. I finally had to get a urinary sling this past winter and now my ejaculations are bone dry, no urine and no semen. But what I have discovered is that Trimix alone isn't getting me to the finish line during intercourse. Since I don't have that surge of sexual stimulation anymore, my erections are less than adequate when lying down. I have to stand, letting gravity do its work, to maintain a good firm hard-on. For two years I have been doing penile rehab with a VED so yes, I do have a tension ring that will keep my penis turgid if need be. But I have to admit, I was hoping Trimix wasn't going to need any help.
Many of you will tell me to get an implant, but I'm not sure my wife will agree to sex often enough to warrant that major surgery and major expense. Has anybody on Frank Talk had the same experiences as me in this regard? What remedy did you come up with?