That is what I am thinking. My truck only has a single 150 gallon tank. The extra capacity would come in really handy and seems like it would be a lot easier to setup than trying to add another side mounted tank.
The last truck I drove was a w900. Strap mounts top and bottom of frame. 2 straps and nuts. 2 fuel lines suction and return. And 2 splitters to tie the second tank in to the first. So fuel was pulled and returned from/to both tanks.
That truck originally had 2 x 120 gallon tanks. They got chopped down to accommodate Masport pump and drop axle. End result was 45 and 65 gallons for a total of 110. Yes it sucked.