The entry door exterior and interior skins on your trailer is FRP as well.
I haven't found it to chip with a table saw, it cuts more like plastic despite the fiberglass in it. You can also use a router on it and route a straight line or flatten out an edge if you wanted.
Many car washes use the same panel on their interior walls, so it's a great product for wet environments. Just make sure to seal the corners sufficiently. Personally I'd put some sort of angle channel in on each corner before installing the plastic, then silicone the corners when you're done. That way, if water does seep into the corner, it would drain down the channel and in the shower pan lip.
2007 T-286SR Cherry/Granola, #6236, original owner, current mileage: 9467.8 (as of 5/26/19)
1997 T-2653 Blue Denim, #5471
1979 12 1/2' MC, Beige & Avocado, #4639
Past Sunlines: '97 T-2653 #5089, '94 T-2251, '86 T-1550, '94 T-2363, '98 T-270SR