Oh, I also put a lag bolt through the brackets into the floor with a 1x6 cutoff on the top side and a fender washer behind the nut on the top side to keep it from pulling through. To do this, I had to drill completely through the floor so be careful that there's nothing in the way. This probably would have been enough on it's own but the 2x4 bracket just gave me some added insurance since water is so heavy and we travel with a full tank most times.
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