I had a client once literally lift her legs up and down and I myself can’t lie down for more then an hour.
If I have a facial I sit up while the mask is on.
I’m weird like that.
What helps is if the bed is not flat, meaning those begs which move up a little at an angle and then Also have regular pillow under your neck and a knee roll under your knee and perhaps if you really bad have pillows under your actual legs . This lifts legs so there won’t be pressure on your lower back.
You can even place a small folded hand towel behind the small of your back.
The more Sitting position you are the better , however that will cause much for stress for the lag technician as her neck and back will be very bad after a set.