A trailers suspension (short spring length) is very stiff and rough riding vs twice as long LDT truck rear suspensions.
Best way to tell if a tire has a balance issue is read its tread wear pattern. If any odd wear then check for a tire tread that maybe starting to separate in spots....bent wheel (radial runout).
A tire..any tire that is jumping up and down on a trailer is most of the time a defective tire. Time for a replacement tire.
I, as others, don't balance any of our rv or non rv trailers tires nor have any abnormal wear patterns for not doing so.
If you feel the need or simply want a balance job done on the trailers tires as "insurance" or "peace of mind" no one is going to think badly of you for doing so.