The next TH I build will be non-invasive. Using webbing straps as hang points and cable/chain/rope to hold the beams will allow the TH to float in the tree. Not swing wildly, just move with the tree a bit.
Large diameter bamboo sleeves would cover the hangers and give it a Tarzan look!
You could consider the TH like a deck and use post/beam construction with a cutout for the tree. allow for expansion of course.
Peter Nelson has written several TH books. Head to a local used bookstore or Google to find out what is being done.
I think that long cables holding a platform could look great. Even with no low branches you can hang it from up above like a chandelier.
Do you have pics of the tree?