If it’s an ex Tesco 8 metre then I would slide the 5th wheel. The 10 metre trailers will be fine. Many a back unit light has been smashed using 6 leggers and 8 metre trailers.
If it’s a single axel ex Tesco trailer then it’s likely to be an 8 metre, Tesco got shot of them due to over loading on the single axel I was told.