This extremely complicated as you also need to consider the bounday layer turbulance created by the tow vehicle.
Rather than get all scientific and running some sort of Computational Fluid Dynamics simulation... how about you hitch it up and take the rig out on the Interstate and do 90... if it rides ok, problem solved, question answered.
Yes, and I assume there’s an effect from there being “road” under the camper and not empty airspace. (Slight compression of air under the tilted camper.)
Still, an estimate within, say, +/- 30%, would be better than nothing.
The Interstate test might get hairy indeed, if the trailer lost tire contact with the road... That’s what I’m trying to avoid!
What if we look at a third way..
How fast can a Hovercraft go...
Thinking initially wheels that support basic movement although fan assisted would be a cool option for trailer positioning...
As you come up to speed forward facing aspects such as hitch and framing keep it all relatively rigid and
I envision electric fans driving a primary air cushion that can be supplemented with air captured using aerodynamically shaped inlets to keep the whole assembly “lifted” from the road surface and tethered to the vehicle..
Lateral stability (tracking) is another issue...
Yust my 2 cents
Put some wings and a tail. Start at the top of a mountain and floor it up to 88 mph. You can time travel.