Finally have a Maxxis issue!

So you folks that are running LT's on a trailer, did the tire store mount them or did you take all five wheels in and have the mount them?

Keep in mind here many higher end trailers come with LT tires.
Having made a living pulling tandem/triaxle/tandem dual flatdeck/enclosed trailers with 15"/16" tires for a living from 7k on up to 22k GVWR I do it both ways. I generally don't replace the ST spare unless its 5 years or older or 7-8 years for LT tires. I operate my RV trailers the same way.

Also when you get in a wreck and the investigating agency sees non trailer tires,,,how will you explain that??

This is internet myth.
There is no state that enforces the use of a ST tires on a trailer. And your tire dealer cannot show you a CA statute (any state) that will back up theories. Nor does roadside dot look for ST vs P vs LT on a trailer.
Some tire dealers or store owners may have a company policy that doesn't allow them to mount a different tire type on a vehicle other than the tire placard.
One F150 Ford truck forum member said a tire dealer wouldn't mount LT C on his truck because the tire placard showed a P tire.
Lots on ignorance on the subject of tire replacement and tire types out here.

Trailers (even RVs) come with LT tires and even P tires.
As was mentioned we used nothing but passenger tires on our smaller campers and truck tires on our heavier units many years before our domestic tire makers gave us the infamous ST tire.