Vacuum hanger for manual stretching?

IMO, the main problem of manual stretching is slippage. Talc and latex gloves doesn’t improve a lot over clean washed and dried hands, but introduce serious pain. Using bare hands, I can hold stretch for about 40-50 seconds max before hand slips off, and it gets quite painful in the last few seconds - the glans just gets way too smashed. I also have to limit my pulling strength, as if I pull with maximum strength, the hand will slip in 15 seconds. Maybe I have to make my hands stronger, however, that would be even more painful, so I don’t think it’s right direction.

I’ve considered using an vacuum attachment to do manual stretching, but the question is, would it be able to withstand the pulling force of my hands? It’s well known that despite being rather short temporally, compared to hanging, manual stretches make it up by sheer force. AFAIK, water-filled attachments allow higher loads without blistering, but how much higher?

Does anyone has the experience with using some (preferrably DIY) vacuum attachment for manual exercises?