Further research reveals some new products that may prove useful in solving this dilemma. I am looking at using these anchors 8008957
They are load rated to 850# if used in conjunction with a shouldered eye bolt rate at 500# I may have a winning combination.
I will take a spade bit or hole saw and remove just enough drywall to allow the anchor to tighten up firmly against the rafter or top plate. Then caulk around the remaining now flush anchor, touch up the paint and I only have a 3/8 threaded hole exposed to screw in a shouldered eye bolt when I want to use the hammock. I plan on screwing the anchors in as close to the appropriate angle for the hammock.
Can You guys shoot some holes in this plan?