This reminds me of the argument I heard when I was a kid. The church I grew up in as a kid said this: "We speak where the bible speaks and are silent where the bible is silent". For that reason no instruments of music were allowed in the church service. A neighboring church said "if the bible does not specifically forbid something, then it is OK". And they had an organ/piano in the church. Who is right?
My DW's 1/2 ton Chevrolet tire tag, on the door, only lists 'P' tires. And yet I see time after time posters telling others to put LT tires on their 1/2 ton truck. Now the manufacturer may recommend that you don't, but is that an absolute? They recommend that you use their oil and other factory parts, but is that an absolute? Is it forbidden to use a super long life synthetic oil that needs changing every 20,000 miles? The factory recommends 7000 miles (depends on vehicle).
Is using LT tires on a trailer forbidden by the US government? If not, then use whatever makes you feel comfortable and safer. Is there any evidence that says using LT tires on a trailer is dangerous to the public? With the number of 'ST' tires that seem to failing on especially heavy trailers, I wonder if they might be dangerous to the public. That might be just a perception being as there are considerably more ST tires on trailers than LTs. If you feel safer using ST tire, then use it. But upgrade to give yourself a safety margin. If you want to use a LT tire to feel safer then do so, but make sure it meets or exceeds the original tires.