Pfoxy beat me to it, but I second the advice to add a subframe, plus one other caution. I looked at a truck a few weeks ago that had only used the factory cross braces, and after countless loads of wood/loam/etc, things look pretty much ready to pop. The headboard is completely separated from the bed floor. I think there is an unavoidable temptation to overload the sheetmetal bodies once it becomes easier to unload them. Common sense, and a little thinking ahead, as pfoxy illustrates, is neccesary. It would be nice to reinforce the headboard/bed connection, too.
Those EZ Dumper type units look nice, but they sure cut down on bed space. I owned a one-ton with the standard aftermarket steel dump body, and that was hard to reach over the sides, and heavy - too heavy, in my opinion. I'll go for the flat bed next time, too, with short, solid sides for loose heavy material, and the regular stake sides for other, bulkier stuff.
I really like pfoxy's idea to relocate the power unit to a better location, where it remains unmunged.
Mark