A guy at work made these (I have several) for me as I have no wood working tools.
My stick house is being eaten by carpenter bees. The traps actually work great, there were 7 or 8 bees in the trap when I emptied it. I should have taken the pic before I dumped the bees.
This guy in the video shows you how to make one. Easy.
YouTube - ‪NO STING BEE TRAP‬‏
The RV application is a little "iffy"... These traps will catch any bee like insect, wasps, yellow jackets, mud daubers, that like to crawl into holes. I figure a couple of these on or near the RV may reduce the likelihood of such insects getting into your water heater, furnace, etc, since these bugs like wood better than metal.
In any case, most of us still live in the stick house, and in my case at least, carpenter bees are a property damaging nuisance.