As far as burning weed goes, joints burn weed when you're not smoking it unlike most glass. Since you smoke them while walking and can not use anything other then joints, I would suggest tightly wrapping it in a bag and sticking it in the freezer to help preserve the freshness of the weed. The less air in the bag the better because the more air in the bag the more water vapor which can get the weed wet.
I also haven't ever heard of THC being absorbed by a plastic bag... a paper bag sure, but not plastic. So the THC might be absorbed into the joint wrapper if you use paper wrappers.