How about used runflats. They have stiff sidewalls like a purpose built trailer tyre?
I see in the Q&A they say those tires are OK on a 1000kg trailer. Given the tire's max load is 437kg, then that's short of 1000kg, even allowing 5-10% on the towball and zero safety margin for overloading the trailer. I'd suggest they are OK only on a light domestic trailer.
EDIT: These from the same seller would be far better.
My mistake - I grabbed the first auction of theirs I saw - It's the link that you put up I have been buying.