Man, some of the cool stuff guys are doing this winter, like Zipper's build, and BMWEuro's 1150GS! I'm a little embarrassed to post up my next mod. All I did was add 2-1/2 gallons of extra gas in a CARB-compliant plastic bottle.
I picked this particular bottle because the spout system actually works! It doesn't drip or leak, and dispenses fuel accurately into the tank (and not onto the tank) when needed. Lots of guys like those 5-gallon metal jerry cans, but one of those would block my turn signal/running light if I mounted it behind the sidecar wheel, and I simply don't like the looks of them mounted up front. Plus I kinda like the way No-Spill Jill handles that spout!
Once I'd chosen the right bottle, then I paid a welder to fab up a cage for it from aluminum. Here's what I got--
I mounted it with four 6mm stainless bolts, with body washers and nylock nuts inside the trunk, and 1/8" rubber grommets on the bolts so that the cage would not be rubbing the sidecar body constantly. Also so dust and dirt could flow past instead of building up. Here's what it looks like--
It's a tight fit and the bottle stays in place OK, but I added the two velcro straps just to make sure it doesn't move. I also had the welder add a padlock tab in the back so if I'm parked someplace where I think pilferage might be a concern, I can padlock the bottle to the rack using a small chain.
The only thing I'm not sure about is how well the bottle is going to deal with temperature changes. Extra pressure can be outgassed easily by pressing the green button on the spout, but I'm hoping it won't be something I have to think about.