The solution is called "Great Stuff". and it is great stuff.
It is an expandable foam.
But.......you must get tons of it in everyone of those holes that pipes or wires come up. You have to take wood panels off and fill areas where they can get up from the basement. For the closet we had to take the wood off where the water lines and drains for in for a washer dryer prep.
For the dresser drawers, we followed some electric lines to a covered panel where they went down, took it apart, filled the hole and then some and put the panel back.
Also, had tons of places to fill around all plumbing and wires in the liv/kit areas.
We have not had any this year, (fingers crossed).
We keep a few glue traps in the basement, but have not found any, I guess if they can't get in they just go back outside. We never store the grill or anything that is food related in the camper or basement either.
Good luck, I don't know any other way unless you want to just keep cleaning up after them or killing them.
Not for me, I will keep finding where they get in and seal it.