No offense meant, but if you have been doing these so called fowfers since you were a “very (very) young boy”, and your PE - “Began 4/9/07” with a Bpel of 4.438 Eg 3.750” - I would hazard a guess that they really aren’t doing much other than providing a comfy spot for you to hide your dick. Many years of ritual stretching would surely have given you a longer unit by now.
I wouldn’t think you would be maintaining enough traction by just placing it behind your butt and then drifting off to sleep.
Every night (and morning) I use a similar technique in bed. However, big difference is I get a good manual grip on my dick from around back of my leg. Pull it around as far as you can - get a good burning stretch going and roll your thigh/butt up against your hand to assist in holding the tension on. 5 minutes aside for a total of 10 before sleep and 10 before getting out of bed.
That is the only stretching I have been doing to augment my jelqing and clamping. So far I am happy with the gains I am getting.