Just for info, I was looking at the 50-gallon in-bed tank along with this midship one. Local installed price was pretty much the same. But, Transfer-Flo is located in California (Chico, I think), and they show an installation deal on their website, at their facility. But, if your DH is the mechanical type, he might be able to DIY the install.
There are some less expensive in-bed options out there, as well. Then there's always the poor man's auxiliary tank: a few 5-gallon jerry cans strapped down in the bed of the truck. I thought about that, too.