Clarification...
*ALL* ladder frame pickups/SUVs has a unibody/monocoque sitting on that ladder frame
Not all unibody/monocoque are the same. The gauge(s), where the abutt, how they
are spot welded together, how many spot welds per inch/foot, dia of spot welds,
how the various panels spot welded together are designed (pure flat to some sort
of geometric shaping to even thicker stiffeners spot welded, etc) and much, much more
Most all unibody/monocoque has stub frames for the engine. Whether front or rear.
Some have truck area stub frames
Unibody/monocoque has to 'WD' (weight distribution) the load/stresses/etc from
where the receiver is bolted to the rest of the vehicle ending up at the other
axle. A ladder frame does that directly via the frame rails.
A unibody/monocoque does so via the other sheetmetal panels spot welded to the
one panel that the receiver is bolted to. That journey through the food chain
of sheetmetal panels is via the spot welds that hold them together...until the
loading/stresses reach the other axle.
A unibody/monocoque 'can do it', but the real question is for how long before
the spot welds start to over stress and fracture. Mystery squeaks and other
noises will be the leading indicators of over stressed spot welds that will then
allow 'movement' between sheetmetal panels.
Bottom line for me...read your manual for 'your' vehicle. Some say no way for
WD Hitch systems. Some yes, but limited by whatever they say. READ YOUR MANUAL
and all the advice here is secondary to that manual for 'your vehicle'
PS...I've lost a lunch bet with a buddy who owns a Cherokee...it does
have a kinda sorta frame...just shaped to follow the unibody/monocoque
body to booster/strengthen the unibody/monocoque body