1) Do you put your pillow on top of your mat or off the end? If on top you lose length and your knees might drop off the end.
2) Do you plan on putting anything down on the ground under your feet?
My "pillow" (fanny pack with a small 1" thick open cell pad on top) is normally off the pad with the sleeping pad reaching to the crest of my shoulder. That puts the other end of the pad 7-8 inches below the fold in my knee.
But I'll need to make the pillow 1.5 inches thicker if I leave it on the ground. The current setup is barely thick enough when on a 48" prolite 3
I put a folded double 1/8 GG Nightlight pad under lower legs mid-Mar thru mid-May and Mid Sep thru Oct (MN) otherwise nothing. Full length pads during winter.