The most of movies are with bad ending. In most cases couple find out they loved too much to fucked someone else etc. Recommend some movies with happy ending cuckold.
When in nudist resort, make some jokes to him, like: "wow, what a hot woman... Would you like to fuck her?" or something like that, and maybe he will do the same. It works for me.
In my opinion this is bad idea. Dont forget your wife have a feelings too and sooner or later she can fall in love with her regular bull. My advice is never go with same bull more than 2/3 times.