The frame I found was made out of 4" heavy channel. The bottom of the frame sits about 13" from the pavement with the camper in place & loaded. Top of the frame is at 17" & the trailer sits on top of the frame. With a 47" wall height for the cabin, my whole rig is about 64" tall. With the vent it's closer to 68" (the highest point off the road).
Detail shot showing the frame. This is about an inch higher now than with the full load in place. The axle has about an inch of drop, but it's hidden in this view. I was worried about the spring travel (2000# axle & not a lot of room), but they seem to do the job well enough with a load & travelling.

Here's the trailer when I found it. Nicely made & very solid. If anything it's much stronger than it needs to be, about 500# stripped & ready for the cabin.

Finished height as it sits behind the truck.
