A plastic 1 gal size container UL approved etc. fits into the spare tire
nicely. Just drop the spare, and flip tire over if needed, then put the can
in on its side, caps tighly closed. A bungee cord keeps it snug. I try to
fill the can to the max so it won't slosh much.  This is worth maybe 20
miles, really doesn't get you too far. Fairly solid place in the event of a
crash, well shielded. I think you can get a round can that fits the rim
better, 2.5 gal. maybe, but the price is way higher.  Tim