Unless he went to the AT and then came back in time to die a couple of weeks ago (so as to have skeletal remains), BL has been in that preserve since Sept 13. I find this the most likely scenario. He went there to kill himself and did. Time of death will be difficult to establish, but they'll make an estimate. That dry bag may provide better evidence as to where he was for a month, through its dust, pollen, mold and mildew.
DNA analysis will allow identification of BL even if remains are skeletal. Just one tooth is enough. The DNA in teeth lasts a long time. DNA in the bones can be reconstructed (which is how we're getting more Neanderthal DNA, even though the bones are 30,000 years old). If the skull is around, it will be immediately obvious to any biological anthropologist if it's BL, IMO, as he had some distinctive features and we get used to looking at skulls and seeing faces instead - but naturally that has to be backed up by other analysis.