i have looked all over the site and not really found my answer so maybe if it is out there someone can let me know. i have a 2007, 5.7. it has the infamous 26 gal tank. when i tow my camper i get about 9mpg, which doesnt bother me but stopping all the time for fuel does. i didnt buy the tundra for its gas mileage. I have seen titan and other companies make a 46 gal tank to replace the oem one but that is not in my budget (usually about $1100-$1600). I use to build custom trucks and we always ran fuel cells. i never had any issues. So i thought about putting a fuel cell in the bed of my truck, and using a manual valve to open it up and drain the gas into my filler neck, like a transfer tank. i have heard mixed things about this but some say it cant be done because its gas and its illegal etc etc....i am going to make mine removable via quick connect just in case i need to use the bed. the tank i am looking at is 17 gals, and is tall and skinny so i could put fuel in it from the ground at a gas station. I would have to weld a bottom bung in, cap the other bungs and the sending unit will not be used. what are yalls thoughts on this? the do this on diesels all the time. why not gas trucks?