I know this is an old thread, but I wanted to say for anyone who doesn't know that you don't have to use the diaphragm. All that I use is a 12 inch balloon for a sluice, no diaphragm. I use a very very small amount of astroglide, use the ball to suck me in, then I remove the ball and release most of the vacuum. I never slip out. I don't get blisters or swelling or anything.
I must note, however, that I do not use the
extender. I only use the belt from the
vlc tugger that I bought some years back but never used. I keep my unit pretty tight, and I use the hip method. Because I've been wearing this for so long, I'm experienced in the different feelings of wearing this device.
With that said, it's not uncommon for me to wear the
pmp head piece for 8 hours straight without checking on it. Not even to pee. I know that sounds weird to go 8 hours without urinating, but I'm a truck driver, and some days I can just drive and drive and not have to stop to pee.
I hope this helps someone.
Regards