I have attached 2 pics of the retrofitted tanks I have on one of our ZR 250 Sky-Bike trikes. This unit is 6 years old and a bit beat up, but still going strong! I purchased two translucent tanks at a lawn tractor shop for about 20 dollars apiece. They are 2.5 gallons each which allows me to max out to the Part 103 allowable limit.
Of course, on a trike the additional 40 lbs. of weight is not an issue and they allow me to really increase my time aloft well beyond anything I would want. This would be a great set up for any pilot wanting to do some serious XC in a trike based PPG.
The tanks are connected by a common crossover line which in turn runs to the fuel pump and then to the carb (Mikuni float carb). The platform on which they rest can also serve as a storage compartment for wing bags, extra maps or a very large lunch!!
When I fly this ZR as a backpack (I almost always opt for the Walkerjet Simon for this), I only fill up about 1/2 way in each tank to keep the weight down.
See picture below: