I just got a Tundra 2 months ago and haul a 2 horse slant with it, usually with just one horse in it. I don't even notice the trailer is there on flat ground, but do notice it takes more to accelerate on the winding uphill to the nearby state park (it doesn't help that as soon as I've gotten up to speed there's another low speed curve!)
I got the 2010 4.6L V8, there's also a larger 5.7L engine available if you're towing more weight.
I've been very impressed with the factory tow package. Adding the brake controller was super easy- it's prewired, so just plugs in below the dash. It was also prewired for a backup camera, which I was also able to install myself and makes lining up with the trailer a breeze.