Look up the billboard adverts for Araldite epoxy glue. Yes.Will epoxy adhere to metal?
As for the aluminum brazing rod: be sure to bring along a couple of stainless steel toothbrushes to thoroughly clean the surfaces of all oxidation before welding. Give it a fresh surface to adhere. I don't know why, but stainless works and other brushes create joints that fail on me. Use a stainless "fan" brush for spreading the stuff too. The right word escapes me, but they are a little fan shaped brush. Don't mess with anything but stainless. When you want them to hold, you really want them to hold!
Nice thing about the stuff: you can bring a propane torch head in your river hardware kit or use the propane from your camp stove to heat larger pieces for repair. Might have to wait your turn or fight with the cook, but they'll eventually let you use the propane.
I don't carry TIG or MIG welders on the river.