The proper matching of tow vehicle to a trailer is an exercise in mathematics and physics and sadly, is poorly understood by many folks out on the highways and byways. I strongly recommend that multiple sources be researched in the quest for the best method of safely connecting a tow vehicle to a trailer. RE: the unibody issue, if the vehicle manufacturer recommends NOT using a WDH, I'd take heed. If there were a situation that resulted in damage or injury, the insurance company and perhaps even law enforcement will side switch the manufacturer's recommendation. Claims will likely be denied and legal exposure could result. Just sayin'!
RE: tongue weight, it is variable and is dependent on "dry weight + added cargo AND how it is distributed. "Dry weight" is nearly a useless value as no one camps without putting "stuff" in their trailers. The trailer has an information sticker that, among other things, will state the GVWR, which is the the "dry weight" + max cargo weight (whch includes propane, water and everything else that is placed in or on the trailer)! The "hitch weight" should generally be considered to be 10-15% of the trailer's total weight (which may be less than the max weight) and achieved by proper distribution of the cargo in or on the trailer.
RE: the tow vehicle's capability, there are several things to consider. The manufacturer makes these determinations and lists them on a sticker. The GVWR (Gross Vehicle Weight Rated) is the "rating" for the vehicle that includes its base "curb" weight + anything it might carry. This includes fuel, driver, passengers, any cargo AND the hitch weight of a towed vehicle! The GCVWR (Gross Combined Vehicle Weight Rated) is the sum of the GVWR and the maximum weight of a towed trailer!
There are no "inconsequential weights" ! The parts of the WDH that are attached to the tow vehicle are a part of its payload. The parts that are attached to the trailer are a part of its cargo. Every pound counts!
If you're not livin' on the edge, you're takin' up too much space!
2007 Shadow Cruiser x210, 2004 RAM 2500 4x4 QuadCab SLT 5.9L CTD, Factory Tow Pkg (3.73 axle), HaulMaster WDH