What brands of tanks are available for extra fuel? I've seen the TransferFlow. I want 40-50 gallons that will tie in nicely with the micro stock tank, Plus I dont want it sticking up above the side of the bed. I saw somewhere a flat one that you could put a toolbox over, but I cant find it now. I just didnt want to spend the $1500 on a toolbox combo from T-FLow.