something about those swimming pool floating foam noodles is screaming potential MYOG.
cut/slice off a 12 inch strip of the 6 ft long noodle.
then slice it length wise, to make two half circles.
can use it as:
1) a neck pillow, it's lightweight
2) a splint for a broken limb
3) connect 2 halves sideways with duct tape (like a book binding) to make a sitting pad.
4) a lousy flotation device
5) add it to retrofit a backpack bag that lacks lumbar support padding
6) sheds water quickly, foam plastic can burn slowly, black smoke will kill you though.
7) store the pointy tent stakes, protect your backpack from tear
8) slice off 1 sq in for fishing float
my ideas are weak - do you have any better ideas?