I think all manufacturers inflate their Tow Rating claims. 7200 is too much for a Tundra to tow safely and reliably...I don't know the Sequoia rating.
Anyway, be sure the boat trailer has working surge brakes, and I'd get an "Equal-i-zer" brand hitch for that rig. It combines weight distributing and sway damping, and is surge-brake friendly.
http://www.equalizerhitch.com/boat.html
RVWholesalers has them for $400.
Ken