Roger your tank was probably designed to be in the trunk, but as a wise man once stated, "improvise, adapt, overcome" and that fits the bill here to a "T". The properties of polyethylene allows for a bit of flexibility that that you wouldn't find in abs or polycarbonate. My only concern is that, IMHO, I would construct some form of skid plate so that an errant rock couldn't damage the tank in the location you will have it placed in and leave you stranded. Just my 2cts. worth.