The prominent tree is indeed the Ren tree. I suppose it would be possible to sleep in the tree, but not easy. I've seen a bear do it by straddling the crotch of a large branch and simply hanging for a few hours while they dozed.
The crabs can and do climb all kinds of trees, but they have to have a reason. The strawberry hermits usually don't climb much above a couple of feet, but the big Cocos will climb higher. If a person were up there, I don't see any reason why the crabs wouldn't get to them unless they were way out on a limb, and that would be a difficult place to sleep.
As for bones, if they were there, we would have seen them. We used the tree for all kinds of things - hanging our packs, machetes, trowels, hammocks, tarp chords, whatever we needed to get off the ground. Interesting thought though.
Green can in my hand is, I believe, Fiji Export, a version of the popular Fiji Bitters. Now a division of Fosters out of AUS. Didn't cause any intestinal disturbances, and was greatly enjoyed at the end of a long hot day - as you can see.