[cagey]

I did something very similar to enable true working from home while recovering (slowly) from a herniated disc about 18 years ago: given a work laptop that opened 180 degrees, using scrap and bits from my garage I hacked together a 1 x 12 pine vertical sandwiched between head of bed and wall, with 1/4" plywood horizontal (with rectangular hole jigsaw-cut for laptop screen) fully cantilevered using eye-bolts and metal chain from vertical plywood extension. IBM Model M in lap, with a (now sadly unavailable) MS optical trackball mouse on the bed next to my right hip. There was enough vertical clearance to easily roll in/out of bed (on my left side). Understandably, my wife only tolerated its marring of our bedroom decor until my back was mostly back to normal...

edit: in addition to the expected pillows for my head, a triangular-cross-section firm-foam knee pillow was an essential component of this setup.