Shouldn't need LT tires on that light of a trailer. I have been running ST's on my FK1900 for severn years and never had a single blowout. LT's are overkill for that size trailer IMO and he would also have to go to 16" rims. Lots of $$$. Stick with STs and you'll be fine. MAxxis is a good choice for ST tires.
These trailers are known for having one major issue and that is sagging outriggers that cause the side walls to droop. YOu can check if yours is affected by inspecting the wheel wells from the inside of the trailer. If they are still square to the side wall you are OK but if they are starting to lean in and separate from the wall, then the wall is sagging and you'll want to address it before it gets worse.
As for your noisy hitch setup it likely just needs some grease on the pivot points.
