I re-ran the simulation, adding a Voluptuous morph to V3, and adding the chair (used 0.1 for static friction for it). It's now a 60 frame simulation: 1-15 crosses the legs, 16-30 adds the Voluptuous morph, 31-60 bends the legs and sits V3 on the chair. (V3's rear does not touch the chair; there's a small gap of about 0.01 Poser units) The simulation takes about 0.5 seconds per frame for 1-30, slows down to about 3.0 seconds per frame on 31-60. I don't know that the extra frames helped anything, I could probably halve the whole thing and get the same results.

It's certainly not perfect, but the simulations are taking me 1-2 minutes each, so it wouldn't be too time consuming to experiment with tweaking it.