In which case I think you already know that the soloution is to never give someone else your bag to look after. Ever.
I know this may sound very odd, but can you build some sort of hide for your things in another part of the park? Or anywhere there is unlikely to be crackheads? Try looking on survival sites and things like that perhaps? If you really cannot carry the weight of your bag, but still need everything that's in it, then that is at least one option for you to think of.
I won't tell you to go looking for hostels and places to stay ect as I assume you are already doing that. Just trying to think of ways to keep your things safe.
Something of this nature perhaps? I haven't read it fully but there seems to be a lot of general survival info all the same. There may be something in there that could help you?
http://www.m4040.com/Survival/Survival.htm