Yellow Jackets and Hornets like protein in Spring and Summer, during fall they prefer sweets like sodas and juices. You can hire a professional to deal with them.
The other option is to kill them yourself. Hang traps around the outside of the camper and in your yard as well as inside the camper. Use the traditional scent bait that comes with the traps
but add canned white chicken meat to the traps. You mentioned you know where they are getting in dust that area with
Tempo Dust. You can soak the area with
Stryker 54 which is a kill on contact spray, this works great in cracks and crevices.
If the area is extremely active during the day, do the stuff at night, the benefit is that most of them will be in the hive and not very active. When you kill a hive during the day, the problem is the hornets or yellow jackets that are outside searching for food eventually come back and now you have to deal with them as individuals rather than a collective hive.
See links below...
https://store.doyourownpestcontrol.c...rin-tempo-dust
https://store.doyourownpestcontrol.c...ker-54-aerosol