I have watched this and other towing threads with interest. There are very good answers with specific details on determining towing capacity, towing loads and tongue weights.
A thumbnail look at your boat with a tank of gas, you are at 7,000 lbs. An Escalade is rated at about 7,700 lbs towing capacity. If those two figures are correct, you are pushing it.
After having towed stuff for almost 40 years, here is my seat of the pants approach. If you know your towing needs, including passenger and gear weight, never tow over 3/4 of the towing capacity. The manufacturer says you can, but what you can do and what you should do are two different decisions.
As you get closer to the maximum towing capacity of your vehicle, you stress the mechanicals of that vehicle to its limit (the straw that breaks the camel's back); engine, tranny, springs and shocks. This stress will wear your vehicle out faster if you are working the vehicle to its maximum. You do not want to drop a tranny while on vacation with your boat. Similarly the closer you come to the maximum capacity of your springs/shocks/etc. you come to the point with your vehicle of not having control of your load. You need extra capacity left over in your vehicle for the extreme hill, the steep and slippery launch ramp, the nut that slams on his breaks in front of you, the heavy side winds of an interstate. Jack knifing your load on an interstate at 65 is enough to have your life pass before your eyes!
Also, you need to look beyond towing capacity to wheel base. I know that is part of the equation when determining towing weight capacity, but some manufacturers tell you stuff about towing capacity in terms of weight only. With your trailer, you are towing a load that is over 30 feet and 7,000 lbs. That tail can wag most dogs. You need a long wheel base truck to keep the truck and the trailer going straight down the road. A long wheelbase truck will of great help in that regard. That may mean your overall length will exceed 50 feet of truck/trailer.
So if it were me, I would be looking at a vehicle that can handle 12,000 lbs. That way it won't be breaking into a sweat to get you down the road. A couple of friends have the new Ford turbo diesels that they use for towing RVs, horses, and construction equipment. They all swear by them. F250s and F350 are tanks, they will take loads all day long. Don't know about the GMC/Chevy duramax. A Tundra is a new product. All I can say is that I would get beyond the 1/2 ton trucks. You need a 3/4 or heavier truck to haul your load safely and reliably.
Bill
Bill Cook
Saratoga Springs, NY
Charleston Lake, On
'08 200LS 5.0L