The problem with the "tow rating" is:
1, it does not specify what kind of trailer... There are dozens of different trailers out there that can weigh #12,000, but have very different tongue weights, loading and aerodynamic qualities.
2, That's essentially a stripped down model they are basing the rating off of.. Most roll out with a few options at least.
3, Vehicles always weigh more than their 'curb weight', especially older models.. The newer models are better because they have that "payload" sticker now..
4, Even if the 'tow rating' was #20,000, the footnotes always say "properly equipped" and "don't exceed GVWR or GAWR"..
So, you are doing well in looking at all this stuff up first and getting opinions from others that have towed before... I've towed heavy before a long time ago from coast to coast towing very heavy loads (construction equipment) in the late 80's/early 90's with 3/4 ton trucks and vans and it was a hand full! I made it just fine and didn't have any issues, but it's not like towing my little #5000 22' TT I have now! :)
Now, you probably won't load up that trailer to it's GVWR of #11,000 pounds, and yes, it's under the "tow rating", but lots of other factors will be in play that are not necessarily spelled out on the ratings and even on this forum for that matter... ;)
What you are proposing to do is possible... But, as was said, to start right out with a 39' rig, towing at the max limits of the vehicle is going to be an 'adventure' for sure! :)
Mitch
