Tough call here.
Personally, on an older trailer that's worth what? $5-8k? in good condition I'd get it covered, let it dry as best as possible. Dunno where in Cali you are, winter and rain or Palm Springs or somewhere in between weather wise.
Seal it up and go camping, and see if the condition maintains or worsens. If you're saavy with repairs and the damage isn't into the framework and you don't have to re-work or remove siding or front cap, it could be a relatively economical fix. If it does involve that stuff, you're faced with a big $ repair that could/will cost a good % of what the trailer is worth AND it would be un-usable once tore apart.