Being so into photography I am sure you are aware of Kirk stuff - http://www.kirkphoto.com/platforms.html
I use the little clamps for various shooting jobs - they are the very best way to quick-detach spotting scopes for instance. You can get a universal dovetail base, I cut them into short pieces and put them on spotting scopes, chrono stands etc
As for non standing-height shooting rests the Nightforce is the best, simple as that. I agree with Dave, gotta use Harris's but I bet I could also sell you guys on Stoney Point also - they are lighter than my Nightforce.