I couldn't put floor to ceiling posts where I wanted them, due to interference with the garage door, and the free-standing wing jig looked like too much work. I borrowed these steel stands and bolted them to the floor. I actually have three sets of holes in the floor, one fixed end, a set for the other end of an HRII, and a set about 6-8 inches further out for the RV-7. I'll just grout the holes when I'm done.
The "rotisserie" feature eliminated the need for shimming when ensuring no twist in the spar, and made for easy access for riveting the main skins to the rear spar:
