Looking for a suggestion on how to repair wall panels?

http://www.lowes.com/pd_8566-293-FTSTF.1_4294715692__?productId=3162499&Ns=p_product_qty_sales_dollar|1&pl=1&currentURL=%3FNs%3Dp_product_qty_sales_dollar%7C1&facetInfo=

This links to a product sold at Lowes that I have used in shower stalls and around bathtubs.  You will also see it in the restrooms at quickmarts on occasion.   It is pretty thin, like 1/8 " and very durable.

If you see that the walls on your trailer are swelling near the bolt holes at the exterior supports you could try sliding a piece of this between the support and the trailer wall with a coating of silicone adhesive against the trailer panel.