The weakest link on your 4 cylinder Taco is said to be the rear end gears, because they use a smaller gear set for the 4 than the 6. If worst came to worst and they got chewed up, you can replace with the larger gear set and be done.
Do not expect to win any races. Figure on driving about 55 mph, 60 at most. Keep it out of overdrive. Don't be afraid to slow down and shift down if it's struggling up a grade, and don't be afraid to rev it; the engine is built to work all day at high rpm if it needs to.
BTW, I was towing the KZ and the 17' Burro with a 2008 Highlander V6. But I know of people who tow the fiberglass trailers with 4-cyl vehicles including Tacomas.
I once towed a 13' egg 2000 miles with an '84 Dodge Omni 2.2L 4-banger and 5 speed stick. Less than 100 HP. It didn't hurt the car any. But we were only going 50 mph much of the time.