Another Extra Fuel Idea + Rear Rack
First, the extra fuel.
Two 1-Liter Sigg bottles (on sale at STP for $6)
1/8” Aluminum (approx. 8”x8”)
Two 5” pieces of 3” ABS
Two small pieces of aluminum angle.
One 1/2” conduit clamp
OK, cut about a 2 3/4" to 3” vertical piece out of the ABS so it can snap abound the bottle. Chamfer the inside edge of the cut so it's easier to slide the bottle into the ABS cylinder (I used a sander). Mount the ABS to the aluminum plate using two countersunk machine bolts. Put an aluminum angle on the bottom of each ABS piece (with some stick-on weather strips to protect the bottle). Mount the aluminum plate to the bike using the helmet lock mounts. Add the conduit clamp to connect the plate to the frame at another logical point. Maybe add a safety strap around the bottles but the ABS should hold them just fine.
Ta-Da. A little more than 1/2 a gallon of extra fuel. Easy to put on and take off if you're just buzzing around town.
Also, made a light duty rear rack from 1/8” aluminum. If it needs to be a little stronger or a bit larger I can just screw another 1/8” plate on top.