I am 5'8" and the Driver's seat on our '21 VTDP 3412 is too deep for my comfort. Also, it is tilted up in the front a bit too much. My legs are just too short for the set up.
I've used a pillow and/or extra lumbar support behind me with some success, but nothing that I like yet.
Our unit has the Villa furniture.
Any suggestions? And, please, no "sit on a phone book" jokes!"