JMO but from my experience I would say way too much tire for the job.
The Sailuns (4080 -4400 lbs capacity) work best for 7k and 8k axles but not the best idea on trailers with light loaded 6k-5.2k axles.
I got into the over tire issues on my tandem axle cargo trailers with 5.2k axles with 15" OEM load C tires.
My other trailers (heavier) with 6k-7k axles had 16" tires so I moved both cargo trailers (our job site tool trailers) to 16" E tires. After that move we found tools scattered all over the trailers floor. At that time we had many 15" LT tires available so went to a 15" C load tire. No more tools shook loose from their hangers/shelves.
I would put those G load Sailuns on CL and use that money to re tire the trailer with a 16" LT E Bridgestone R-238 commercial grade all steel ply carcass like the Sailuns if they fit or a ST E tire like the Provider....Endurance....Carlisle HD in that order. These are a better class ST tire than what we used 6-8 years ago.