Our last TT was 20' weighing 5,000 lbs. Towed by a 2000 F150 with a V6. The truck suspension was fine but the engine was terribly under-powered. On steeper sections of the interstate, we were on the right shoulder with the semi trucks crawling along at 30-35 mph flat out. It had trouble maintaining an even speed in gusting winds. The engine was running flat out most of the time trying to make enough power. On an 1800 mile trip through Oregon and Washington, we had to stop at a Ford dealer 3 times to get engine work done. We had it taken to one dealer on a flatdeck tow truck. That little V6 just wasn't up to the task even though we were well under the max. towing capacity. Never had any engine trouble in the 10 years we had the truck until we started towing that trailer.
The TT was 3500 lbs dry but ended up at 5,000 lbs fully loaded and the GVWR was 5,000. It doesn't seem to take much to get 1500 lbs added to a TT, but it all adds up. If have to check, but the engine put out something like 220 HP as a reference. The F150 would be a heavier TV tho.
I think unless you have something like an ecoboost V6, you will have trouble. JMHO based on personal experience with a similar TT and engine. At 3.0 liters, that's awfully small. Our V6 was 4.6 liter (IIRC) and tow rating was 5800 bs. I don't think I'd want to do 1400 miles with your TV. I have to think you could end up with overheating on longer/steeper hills.
Aha, it looks like you (OP) revised your engine size from 3.0 to 4.0. :) Looks like '01 specs say 210 HP. Not much less than our F150 was and I think you may still find the Explorer struggling up some hills.