Actually, they found and interviewed the guy out in Calif. who got in the suit and played bigfoot, because of the funny way he walked (still walks) - him and his buddies admitted the whole story in great detail after Patterson died. Patterson paid them like $1,000 each to go out and help him make the film - they trekked a good ways into the wilderness on horseback. Just some good ol' boys.
http://www.rense.com/general49/making.htm
http://en.wikipedia.org/wiki/Patterson-Gimlin_film