Hi: Ambrose... IMHO what you gain with the 19'er is a strip of floor about 6" wide and a little more storage space.
We have a Delta diamond plate lock box that fits behind the cab and is under the tonneau cover.
The ease of hook up and the positive tow+ the bed layout and largest bathroom sold us on the 5.0.
Storage space is not an issue which ever trailer you chose. Our problem is we need more STUFF!!!Alf
escape artist N.S. of Lake Erie
p.s. at the toll booths the 5.0 is only+ 1 axle not 2 for the extra chg.