When I tried on retreats to "keep the sexual energy" as I was advised, it end up being a disaster. Restless mind, strong fantasies, poor sleep. Maybe it would be fine if I taped off over a long period of time but for a short retreat it's advisable. Actually, for men it can create prostate inflammation (something I experienced long time ago, I remember the advice of the doctor to "get it out regularly"). My advice for a retreat is to have sex only before going to sleep since there is effectively a drop down of energy in the hours following.
If you have set rules for retreat, stick to them without fail and examine any resistance as it occurs otherwise there's no point in setting them in the first place.
I don't know about your claims that not having sex can lead to inflammation of the prostate, but perhaps someone with more medical knowledge could clarify this? I can tell you from experience that not having sex, or masturbating, for an extended period of time, in my case around two to three months[1], did nothing of the sort but did reveal considerable insights into my previously rampaging libido. Bear in mind that this body functions automatically and if the need for ejaculation did arise then I'm fairly sure the body would make this happen one way or another i.e. "wet" dreams and suchlike.
There are ways to direct sexual energy towards developmental progress which may be of interest to you if you're not able to remain chaste for a short period of time, but this is beyond the scope of my knowledge and better learned from someone well-versed in the techniques.
[1] I won't go into the details, suffice to say it wasn't voluntary but after about two weeks I chose not to masturbate either and see what happened. This was unconnected with meditation or any sort of attainment, it was the result of a personal situation when my partner and I split up which I decided to use as an experiment in self-discipline.