Originally Posted by clutch
That smallish V6 will work very hard even with 3500#. Keep it out of OverDrive.
The 4.0 V6 is actually one of the larger displacement V6s out there and is a very strong motor. Having towed 4,000lbs with Toyota's older 3.4 V6 (the trailer was not a TT), I do not see any problem with the engine keeping up with a 3,500lb trailer. Keep the tranny in 4th (it's a 5 speed) and you'll be fine.
I'd be more concerned about the short wheelbase than anything. Braking shouldn't be a problem as my boat doesn't have brakes and the 4Runner stops it fine. Having trailer brakes will make it that much better.
Would a larger vehicle pull this load better? Yes, but that doesn't mean it can't be done safely and enjoyably with the 4Runner.
Now that you've got the WDH, hook it all up and don't look back!