For several years we had problems with Stink Bugs and here's how I resolved the problem.
First, pick up 5 or 6 bug bombs (depending upon how big your camper is). Put everything away that touches food and cover it. Remove blankets from the bed, but leave the mattresses.
Set one bug bomb in the front of the trailer, one in the back of the trailer, one in the bathroom of the trailer, one in the pass-through of the trailer, and if you have a fifth wheel, remove the back wall of the pass through outside storage and put one inside that open cavity under the upper floor living area.
Now.... turn on the air conditioner fan on high and let it run. All slides out. And now, set off all the bug bombs at once.
Why do you want the air conditioner fan running? So the bug bomb chemical will suck up into the air duct vents and any holes or openings or cracks in the duct work will suck the chemical up into the ceiling area of your camper.
The bug bomb mist will penetrate everything, including any gaps in your slide out seals or anywhere air can come through. It will put a layer of the chemical in the tiniest of cracks so when any bugs attempt to crawl through, they will touch it and it kills them.
Let the air conditioner run for a good hour at least and YOU stay out of the camper and any living animals, get them out too. After about an hour the odor from the bug bombs will disappear.
No, go back into your camper and wipe off your kitchen counter, chairs you sit on and any surfaces you use. Do not wipe down the walls, ceiling, and simply leave the floor alone until the next time you need to mop it.
What will happen?
You will notice dead bugs everywhere. The next day, you'll have another pile of dead bugs everywhere. The next day, you'll have another pile of dead bugs everywhere. This will continue for about a week. Then, the dead bugs will slow down, but you'll still find a dead one every now and then .... for a while.
Now, it's very, very important that 2 weeks later (actually 10 days), you repeat this entire process one more time. Why? Because those bugs lay eggs and the eggs will hatch out. You want the babies killed off too so they won't reproduce inside the walls or ceiling of your camper. Yes .... that is where they are hanging out. You've got to get the bug bomb chemical inside the walls and ceiling and under the floor.
You will continue to find dead stink bugs for about 6 months every now and then. But, they will be dead.
As a precaution, wait another 10 days and do this a 3rd time. This time .... run your furnace (yes, it's hot, but you really need the chemical pumped through the air ducts in your floor too, and any cracks or holes in that system will also put the chemical under your floor.
I promise you .... if you do this as I've described, you will have absolutely NO bugs for at least 2 years .... absolutely none. In 2 years, repeat again, once with the AC and once with the furnace. After that ... you will never, ever have bugs again. Even mosquitoes will not be a problem and flies will drop dead on the floor.
Also: If you wipe off your counter top and the chairs you sit on and if your dishes and cook wear was all covered or washed off, you will have no residue to worry about.
Just for safety measure, I do this every 2 years.
And note! If you use the spray stuff in a spray can, you WILL NOT get the same results. That stuff just falls to the floor. It's too heavy. You need the light stuff that the the AC or the furnace will pick up as vapor and send it through the duct work and into the open cavities above and below the living space of your camper.
This works.
FYI: I get my bug bombs (4 or 5 to a package from Dollar General. It's much cheaper there and it's the same stuff you pay a fortune for at some other major chain store).