We have RR bridges with 11'6" clearance, why not go with a pop up and stay low to cab height, you're probably not concerned with mpg, but that might help too.
Yeah Pop top (hybrid) hard side trailer is way to go. It's been done on same vehicle infact.
Search Bill Caid. His website shows subframe build. Similar to Unimog. More complex.
Also
in concept there may be a way to do a 3pt subframe; air bag softend, Sprung and with rear central pivot point. All that and may not create much height change. Might even be inexpensive if you use camping trailer using a camper cabin.
AKA-
Lift camper up for mounting
. hire a roll back wrecker to lift your trailer. Roll it onto the stripped bare/modified bed (rear trailer facing cab)
Create a Hybrid 3 point Pivoting Sub frame using bumper pull camper's own frame and suspension system)
Your central pivot point and first mount of your 3pt subframe:
...... Cut the Tounge off the trailer and weld ball coupler back on to trailer frame just under edge of camper wall?
...... Fabricate bolt on trailer hitch too match newly located trailer coupler. Mount this to trucks chasis.(closer to end of chassis the better?)
...... Hook trailer to ball.
...... If needed; optional bump stops and / or shock absorbers can be added at this end.
Mount of hybrid two fixed point mounts further up toward cab?
..... this is an air bag softened/sprung Cabin mount (AKA- trailer tires with lowered pressure. Maybe smaller tires to reduce hight?).
..... Add a few other tie downs to lock it to the bed (around trailer axle?)
..... consider option of moving rear axle further back toward end of Trailer along with needed bracing. Moves this two point mount closer to the point of of truck chassis's ladder frame that has less flex. (usually somewhere just behind cab)
WHALA...... your done.
Granted that is over simplified explanation... but in concept.. hmmmm [Elmer Fud voice] Vewy Intawesting[voice off]
Refercence photo of 3pt subframe on Steyr camper conversion. A screen grab from Youtube.
![3ptBoxMountStyr.jpg 3ptBoxMountStyr.jpg](https://expeditionportal.com/forum/data/attachments/268/268343-62e02627723b73f71f4d84f2ac44aeb4.jpg)