As I have added a quick connect to the existing propane system so that I can use a second tank, I travel all the time with a second tank. I purchased a propane tank holder available at any RV store, bbq store or at the dump off of an old bbq and using two bolts and wing nuts attached it tp the back bench. When I am camping I just loosen the wing nuts and take the tank and holder out. It takes about ten minutes to install and about thirty seconds either way to use. 
    Now as for the larger gas tank(let me put my banjo down) take a large jerry can add a crossover switch before the fuel pump and one of the lines place securely at the bottom of the gas can which is conveniently positioned between the two front seats-your significant other can hold it at the bottom. Now when your main tank empties flip the crossover and voila!!!And you thought that a propane tank banging around in the back was dangerous hehe. Patrick 85 westy, appin Ont