Here's a solution, it works, but for some reason a lot of folks are hesitant to do it...
Clean everything up in your camper. Put away all food items, dog bowls, dishes, everything.
Then set up a bunch of bug-bombs. 3 or 4 in the living areas and one inside the front pass through, or the underbelly if you have a fifth wheel.
Set them all of at the same time.
You need to do this twice, about 10 days apart.
First time, turn the AC fan on and then pull the bug bombs. This will circulate the chemical though you ducts in the ceiling and any small holes or open joints, blowing chemical in all those spots you'll never be able to reach.
10 days later, do it all again, only this time, turn on your furnace and make sure the furnace fan blows non-stop. This will circulate the chemical UNDER the trailer, again, any holes or joints not sealed in the duct work.
In addition, the bug bomb mist will penetrate ever nook and cranney in the camper, any holes where bugs can enter, around the slide seals, everywhere.
Repeat again in a year, (the two time method), and you'll never have bugs again in your camper.
For ants, I've found nothing better than Terro ant killer. Set it out, the ants eat it, take it back to their nest and spread it to others. The entire colony dies out. It takes about 2 days.