Sensual hogtie Bondage! (Plus Watersports)

I have this scenario in mind. It goes like this; I completely undress, with the exception of my under First, I tie my ankles together(I use chain, but rope would probably work better), next, I cinch together my knees. I run a rope around my waist and tie it off loosely, and then loop a chain around the front, with the two halves on both sides of my cock and balls. I run the chain through my legs and lock it in place, leaving only a little ease. I then run a second chain beneath the two halves which constitute the crotch chain, right below the base of my balls and loop it around to the top, where I secure it off tightly. I make sure that nothing… slips out while I’m doing this step. I then untie my waistband and retie it much more tightly, and the crotch chain ceases to be so benign. By now, I have created a very thin, tightly fitting cock and ball bag, which is the desired effect of wearing the underwear(plus, the tight chains don’t chaff the delicate skin so easily). I then run some rope through the chain around my ankles, tie my wrists together with a different rope, and tie that rope around the one around my ankles to make a hogtie. The idea here is to lie with my knees pointed up and my feet flat on the floor, with my back arched to where my crotch is above my stomach and chest, and then either ejaculate or urinate, to where it would soak through the thin cloth and run down my stomach and chest. The posture is pretty much honor bondage, as I could easily bend into a position where my urine or semen wouldn’t run down my body, but then I’d run the probable risk of getting it on the carpet, which wouldn’t look good in front of my parents. The major problem here is that I don’t know how I’m supposed to ejaculate with my hands tied behind my back. Any suggestions how I should do this? Any other advice on how I could improve this in general? This can easily be a strict self-bondage position, but the way I wear it I can get out of the wrist ropes with a bit of effort.