You might have better luck advertising on CL. I have been part of a GB Crew for about 10 years. In our heyday, we recruited maybe 2 to 3 girls a year... Amateurs all. On occasion, there was a husband present. In one case, the husband had us set up his camera on a tripod and film six of us banging the stuffing out of his 98# spinner wife while he waited at home...
This is a pretty common fantasy for a lot of women I think. For every one we saw, we probably had five apply. One of us would always meet the lady a few days ahead of time to (a) make sure she was real, and that she would follow through, (b) make sure she was "hot enough" and (c) reassure her that we weren't a bunch of serial killers.
We have kinda petered out in the past year or two, but mostly I think it's because we have done maybe 15 of these or so, so the novelty has worn off. It is great fun, especially once the guys become friends.... or at least friendly.