Easiest way to safely get the most out of your tires is to bring the trailer home from the dealership, put it up on blocks, remove the tires, and never move the trailer again. Ever. I bet I could at least double the life of the tires that way.
Or I could realize tires are a wearable part and not stress over it. Couple hundred bucks over the course of a few years is not bad. Especially considering these trailers are basically toys, not necessities.
I buy ST tires, usually Hercules, about once every 3 or 4 years. If one blows out, I don't typically freak out. I usually just put the spare on and figure on replacing at least two tires when the trip is over.
If I find the Shaman spell that turns a tire into a miracle, I'll share it. For a price