What I am going to do is tell you how I have done it, in case it is helpful to you. All 4 of my kids have been in undies during the day by their second birthday with essentially no accidents. My last 2 have been night time potty trained by this age as well. This method is a bit of a time commitment and I have cleaned up some unpleasant messes. However, all-in-all, potty training has always been a very low-stress process in our house.
I was checking out my photo album. I realized I have been lying for a long time. Big fat lie. My son was 4.
Of course the campground has toilet facilities. But imagine waking up in the middle of the night to pee. What if the outhouse is like, 10 mins away?