I've been learning a bit about tires, and talked very recently to a friend who works at a tire shop. Besides confirming something I already learned on this forum (which paid for the cost of membership many times over - fill up your tires on your TV to max sidewall pressure), I asked about the need to balance the tires.
He said, YES, balance them (I'm going in tomorrow). It'll help the tire run cooler (less sidewall flex) and the bearings run cooler. He also indicated that it's rather normal for trailer manufacturers of all types to not balance their tires - so TM is hardly unusual here.
Balancing them seems like a pretty cheap thing to do to hopefully prolong the life of the tire and prevent damage to the vehicle.