Just did my 5000lb boat towing experience. No problems, not squirrely at all, in fact it's one of the better tow rigs I've used (experience includes 1st and 2nd gen tundras, Yukon XL's, F250's) notwithstanding Canyonero's experience. Highway...
Just did a bit of towing with a 2000 lb load with a utility trailer. Got it up to highway speeds both in the freeway and on bumpy back roads, was completely and utterly stable, auto leveling feature worked nicely.
Have the 5000lb boat to tow...
I also saw the Slee sliders at Expo Mountain West about 2 weeks ago and spoke with Christo Slee directly. He personally walked me over and had me crawl under the LX to confirm they are indeed frame mounted. 100%
Hey Docyota do you mind if I ask what feet you are using with your crossbars? I wasn't able to find anything that fit well... everything seemed slightly off.