im planning on driving my newly restored/ refurbished (1978) fj40 diesel (1hz engine 20+mpg) through mexico and down to Peru. im all about off the pavement travel. the tub is currently off and being painted so now would be a good time to make changes. do i need a bigger tank? or is the stock tank plenty. is an aux tank a wise move for long range unknown fuel access and which one? under seat, under rear bed? or just use a couple of geri cans. vie never done this type excursion and want to prepare best i can any exp feed back is well appreciated.