I buy the Black Flag or similar bait stations, they look like little plastic pyramids or domes and are available in most all home improvement and department stores. They are inexpensive at just a few dollars for a pack of 4.
Find the ant hill or hills under or around your camper and place one of the traps on the path the ants are traveling. In addition put one wherever you see the ants inside your camper. By the next day there will usually no longer be an ant problem.
Be sure any food or spills that might attract ants is cleaned up. I use zip lock bags for any opened food packages.
If you have pets make sure you follow the package directions and keep them from possibly eating one of these bait stations, they do contain chemicals that would be harmful (that's why it kills the ants).
This has always worked for me, your mileage may vary, no warranty is expressed or implied, use at your own risk.