I basically agree with your explanation, but there is a little problem :
it should be a consequence of that explication that mild erection would be more beneficial, when pumping, if I’ m not wrong in something. Adversely, as ThunderSS pointed, and near any guy who tried pumping could agree, when pumping there is more lymph build-up with lower intense erections than with peak erections.
This is why I supposed that others tissue than tunica could augment their volume more easily than tunica, so the effect on these tissues are worse then when we clamp, and effects on tunica are lower.
But it seem you don’t agree.
So, what are we missing?
I think that the reason there is less edema fluid build up at peak erection is because the skin and tissues below it are pulled taut and are essentially splinted next to the tunica This decreases the capillary fluid leak caused by the negative pressures (for reasons I will not belabor here, unless you really want me to). At lower levels of erection, the effect of the negative pressure on the capillaries are unrestricted and this is why the fluid build up is higher.
I went through a rather extensive reason why the formation of edema fluid would be less with clamping than with pumping in an earlier post in this thread. I think I would make most of you guys nauseous if I tried to repeat it.