Well that is better than "intimate while urinate". I until I got my IPP (inflatable penile prosthesis) I could only urinate and no intimate. So what you have is not that bad, like having no pc recurrence being a big upside, just being able to be intimate is a big plus. I have heard that in addition to maybe planning ahead on fluid intake and a pit stop before, you might be able to get some relief by wearing a constriction ring like the vacumn erection devices have. You can buy just the ring and maybe there are some designs that are easy to apply and remove? my old VED came with a ring launcher that could be used just to apply the ring. Since the IPP, I have a minor problem with what you are experiencing but I have been able to control it with pit stops.
Now for a little biology, after RP you only have the external sphincter and that sphincter is wired to open when, or actually before, you ejaculate, this is so the fluid can travel to where is is needed to impregnate. In fact that is why most people who have not had RP can not urinate when they a sexully stimulated with an errection, your reproduction system has opened the external sphincer and closed the internal sphincter. You have no conscious control over the internal sphincter, thus you can not pee until the errection is gone.