Your out camping. Your door is so secure it's even hard for you to get out. All your
windows are open and the highest security you have is the window screens over the
windows. For the most part no one wants to mess with someone in their home, they will wait to enter your trailer when you're out on an ice cream run.
If I was worried I would use a deterrent like an alarm mat. Might just move the undesirables on to easier pickens or if you're in the trailer give you a heads up so you can get into defensive mode.
Pepper spray inside your trailer is a very, very bad Idea. You will probably scrap your trailer do to the contamination and how can you evade a perpetrator when your eyes are burning and you can't see where you're going?
Keep your car keys with the alarm button near you when you're sleeping. Its loud enough to ward off undesirables and piss off everyone in the campground at 2:00 am. But you will gain attention.
Walk around the campground with a big brown dog with white shiny teeth so if anyone was thinking about messing with you they look for easier pickings.
look into something like this. I have never used one or needed on so your on your own here.
http://www.amazon.com/EasyAlarms-Pre.../dp/B001QC98RC