My take is the V6 will have enough power to tow two sleds fine. The Tundra is going to be a WAY BETTER tow vehicle, especially on the highway.
If your trailer is a typical snow machine trailer (side-by-side clamshell design) the lower body height and narrower width of the 4Runner means the whole set-up is even worse of an aerodynamic trainwreck.
My guess is you'll end up cruising at around 70mph in 4th rather than faster in 5th. I hate to be a 'spoiler' but the reality is the T4R will handle the weight fine. The V6 and the transmission work well but frontal area of the trailer is going to make the trailer seem much heavier/bigger than it is (as speeds increase).
Any doubt? Tow a fairly narrow utility trailer loaded with rocks and then tow an empty box trailer... I'd rather tow the rocks down the highway any day. (Obviously braking is a different topic, of course the empty box trailer will stop better).
Does that mean don't do it? No, just have your expectations in right place.
