It's a tempting idea, but the Oleyniks we used had beavertails and much lower rear sill (floor) height; yet the ramps still had to be at least 8 feet long and positively lock into the sill.
Very tough deal to modify the rear rails & floor to make a beavertail out of a "normal" box truck.
I've seen some moving vans that sit lower, but still iffy on load height and then there's the wheelwells.
Medium-duty truck maintenance is not like working on a pickup; stuff might last longer, but it's half again as large and seems like triple the weight!
We'd get a million miles or so out of a GMC 6500, but any wheel/tire/suspension/brake/drivetrain maintenance was a back-breaker.