Hottbpete,
The largest spa I have put the Cover Caddy on was a Hot Spring Envoy. It's easily installed and seems to be a quality lifter. We have one on our HS Vanguard on the floor because of wood accessories mounted on the sides. Never had any issue with it.
My only complaint is that the cover is almost too big to slide in there. I wish they'd make the arms a little taller in the openings. I've never used the two wood strips, but that's going to depend on what type of tub you are putting it on.