My opinions in addition to the good info already posted and congrats on figuring it out
Many...most newbies will take the brochure MTWR (Max Tow Weight Rating) as an absolute. Meaning that if it says your MTWR is 9,000 lbs...it applies to all conditions of how your TV is loaded
Not so, as you have found out. If the TV is loaded up to its GVWR, there is no room left in the ratings to tow a 9,000 lb trailer
OEMs are getting better...IMHO, think the warranty/service costs drove them to be a bit more realistic.
MTWR used to be based on the 'curb' weight of the TV. That meant a stripper model with NOTHING other than the trailer package. Marty is the only guy here that I've found to have owned one of those. Today, think that stripper is no longer available...where as it was the government that purchased them
Also, the GCWR is fairly new rating and is performance based, which IMHO has a warranty component. Mainly getting it going on the maximum conditions of everything. Ambient temp, incline, altitude, etc, etc.
Best is to load up the TV as if going RV'ing with people, pets, luggage, ice chests, etc, etc and go weigh it. Axle by axle. That will then provide the true base line to figure out that TV's MTWR and of course staying within the GAWR's
