Hi Joel,
Interesting dilemma. I am surprised it has fed for as long as it has! Does it have all its legs? There should be 6, but sometimes the front two are "hidden" when folded in against the body. If all the legs are there - and working - then I am stumped. If missing, it could be the cause of not being able to land and to "get off the ground." But they also "taste" with their feet so I am assuming he has them all and working. Btw, it is a male, you can tell by the scent glands, on the hind wing (see link below)
PHwyvern raises a lot of these and will hopefully be able to help you out more. When the time comes that he seems to be giving up, you could lay it on a tissue in a plastic container and another on top, then cover. Place in fridge for about a day then into the freezer. You can then mount it in a Riker mount (in batting, not pinned). I am NOT a collector, but if nature has limited one of her offspring and has come into my hands, I feel it is OK to do as it is educational.
lele
male/female monarch