Used to have a 50 gallon in bed tank with electric pump. Sold that truck. Will be getting another in bed tank for my new truck.
For me it had nothing to do with money. They aren't cheap and it'll take years to recover the cost with fuel costs. It was all about convenience and range of travel. Security of not being without fuel. And the ability to help a few folks out when they ran dry.
The weight is huge. Diesel weighs about 8 lbs per gallon. Do the math. Don't forget to add in the weight of the tank. I was just over 500 lbs. That's a lot of payload capacity taken away.
Also don't forget to keep a fuel stabilizer in it, rotate it out every now and again, and keep that tank full when possible
