Sleep in "Zero Gravity Chair" with neck/back pain?
I can’t sleep for more than 3 hours in a regular bed because of neck/back pain. Has anyone tried sleeping in one of these?
I have tried neck pillows, Tempurpedic mattresses, pillows between my knees etc.

I have not heard of a zero gravity chair. Have you tried to sleep with a cervical support neck pillow (one with an indentation in the middle) and two pillows under your knees? This position of sleeping will decrease the pressure placed on the lower back muscles and bones. IF you sleep on your side, take a pillow and put it in between your knees.
You can buy fancy positioning products such as a knee elevator: http://www.arc4life.com/site/615058/product/KneeElev5404
To place under your legs while sleeping. For sleeping on your side you can try the spinal relief pillow: http://www.arc4life.com/site/615058/product/SpinalReliefPillow1107- perfect for placing in between your legs when sleeping on your side.
Finally, have you tried The Cervical Linear Traction Neck Pillow by Arc4life? If you have neck pain- this pillow will be something you want to try. It has two sides to it- a support side and a traction side. The traction side with give your head a gentle lift while sleeping and keep your head and neck in the proper position for sleeping. This cervical traction neck pillow is not going to be hard like the tempurpedic pillow- and it is not going to be soft like a feather pillow. It is called a cervical support neck pillow because it supports your head and neck in the most natural position.
Hope this helps.