I've owned 5 4.7's (AC, DC, Sequoia). I've owned 3 5.7's (CrewMax). I've owned 1 4.0 (DCSB)... and 5 3.4's.
There is a major difference between pulling 3K and pulling 3k EVERY DAY. Personally, I would never do it in a 3.4, 4.0... and frankly, may not even do it in a 4.7.
Having said that, one of the nice-to-have is small and nimble... and since you have a 3.4 now, almost anything will be an improvement.
If you want to stay Toyota, I would consider a 100 series or an 06-07 Sequoia - especially if you can find one that has rear air suspension. The Sequoia will be cheaper, but bigger. And it has the turning radius of a small country. But is otherwise nice.
Of the rest of the list -
Having driven 1 4.0 Frontier... one time... I don't like 'em.
The Colorado will have the DEF issue. DEF pisses me off - my F350 has it. But, otherwise a good choice.
A full-size extended cab could be a good choice as well... but I'd go for a 6.0, 6.2 or 6.4 (gm/ford/dodge)
EDIT: Just dawned on me... Does that trailer have brakes????
If you go down a Toyota route, outside of a 2nd Gen Tundra/Sequoia, you *WILL* want to upgrade the brakes. I had excellent experience with Hawk/PowerStop combinations on my gen 1's. Getting up and running is one thing... stopping - completely different