Tool box/ fuel tank

[prariepoodle]

Well got the nerf bars on the truck today so I don't have to crawl in on hands and knees, was thinking about getting hubby a tool box and heard that they make one with a 50 or 60 gallon fuel tank in the bottom of it. Do any of you have one of these and what do you think of it? Won't it make the truck have to much weight with the 5er hooked on? It would be nice to be able to go a lot of miles before having to fill up. So what do you all think?

Linda n Walt n kookie
2003 3280RL
2004 GMC 2500 duramax 4x4
G-Great
M-Montana
C- Carrier
KOOKIE RULES!!!!