Tacoma? Yikes. Only in an emergency, where there aren’t any other choices. I understand that towing and payload capacities are getting into the neighborhood for the weights involved with towing a horse… but I would only haul an empty aluminum two horse with a Tacoma.
My Mom had a Tundra that she hauled one horse with, in an aluminum two horse trailer. That worked fine, but you couldn’t add another person, horse, lunch…it had the towing capacity but not the payload capacity.
Please educate yourself as to the difference between towing and payload capacities! A sort of close comparison, to give you an idea, would be with a horse… you can only put so much weight in the saddle (‘payload’), but the horse can pull a lot more weight if it’s hitched to a cart or wagon of some sort (‘towing capacity’).
Payload capacity is determined in order to advertise a high weight. So they calculate it with an empty fuel tank and no people inside. Add an emergency toolbox, full size spare tire, two people and lunch in the cooler, a full tank of fuel and maybe a dog… and you can’t add very much trailer tongue weight if the payload capacity is in the 1500 pounds range.
So anyway… the newest “half ton” pickups that have 1500+ payload and 7500+ towing capacity will probably be fine for one horse in a lighter bumper pull. More than that to tow regularly and you really will be in a three quarter ton or bigger pickup.