We had an 04 Explorer V6 when we purchased our 3023, it did fine on the flat land, even though I always felt like it was having to work a little hard. But we spend as much time as possible in the mountains each summer, and it really struggled to make the grade
for example going up I70 west toward the Eisenhower tunnel I felt like I was just working it way too hard, and forget ever coming back from the west toward Denver up that grade, I honestly don't think it would have made it at all, we didn't even attempt it.
I up graded to an 08 V-8 but this summer we went to Prince Edward Island Canada, and didn't really test it in the mountains, however in the very large hills of New Brunswick it did much much better than the V-6 would have.
So bottom line is if you think you will be in the mountains a lot, and living where you do I'm sure that is the case, you should stick with the smaller model of TM. Otherwise you will find you need to get a more substantial tow vehicle.