quentinlindsay -
If you already know the answers - why ask the question/s?
Yes - there are lots of folks who *successfully* tow heavy trailers
with SRW pickups - - WAY beyond rated capabilities.
"Officially" that's wrong, illegal, etc., etc.
Get in an accident and a sharp attorney will dig deep enough to produce the *legalities* involved .....including proper driver's license.
A friend has a 2004 Dodge CTD, SRW 3/4 ton (he did add air bags), and
has towed his Alpenlite (they're not light) 36 footer that has an unloaded weight somewhere north of 14K - thousands of miles including multiple trips to Alaska.
A Toyota has towed a Space Shuttle.
Besides "ability" to do so, does the "go" match the "whoa"?
Suggest you spend some time on the Escapees MDT and HDT forums.
Lots of folks who have "worked their way up" from LDT to MDT to HDT.
Quite a few Maple Leafers there (for licensing input) - along with lots of folks who can match your engineering skills - including a guy who manufactures the (unquestionably) best 5th hitch available anywhere.
AMF and best wishes to/for a happy and satisfactory Q & A session...:C
~