While it is pretty impressive that your Tacoma can pull that trailer around it seems like it is asking a little much of the truck. If you decide to step up to a full-size truck i2n the future I highly recommend a F150 with the 3.5L EcoBoost engine, given your needs. They're not too bad on gas for normal driving (similar to a Tacoma) but they also have tons of power and low-end torque when you need it. It was between the F150/EcoBoost and the Tacoma when I was looking for a truck and I opted for the Tacoma because I don't do much towing and a smaller truck works better in my area.
Drive safe and enjoy your travels!
On my first trip, I towed across the southern states, close to the Gulf. Not too many steep inclines there...about the only real incline was the bridge over the Mississippi River. My speed held at 50 mph without downshifting.
I'll only be towing this TT 3 times a year, in between the wife's assignments...not that often.
In the future, I may go up in size for a tow vehicle, but for now, I'll keep the Tacoma...its proven its worth.