Funny, I'm thinking the opposite. I've done over 100,000 miles with my Tacoma and Eagle setup.
My Tacoma itself has over 200,000 mies and I'm searching around for what to replace it with.
I was considering a Full Size truck, because though I've been doing this for years and many many miles I've always known I'm over weight in the Tacoma.
To make the Tacoma work, however, I do have custom springs and lift and upgraded gearing. I think if it was stock I would have changed the truck out years ago, I just recently in the last 3 years started towing a motorcycle trailer with my setup, this is where things get a bit crazy and I've now said, maybe it's time to go Full Size?
Just my 2C...the 2nd Gen Tacoma is pulling off the task (with modifications) but I think keeping your full size will let you have more choices of setups?
With my gearing change I get about 15mpg with the Eagle and about 12-13mpg with the Eagle and towing the motorcycle. If I go down a tire size I can get the truck to about 17mpg with the Eagle and I never towed the motorcycle with the smaller tires so I won't have figures for that. Don't expect great gas milage from the smaller truck.
Best of luck with your new Eagle!