You have to plug all the holes the manufacturer has left just for the mice!
1. At night in a dark area turn your lights on in the RV.
2. Crawl underneath and behold you will see the light coming thru all the places the mice are using to get inside your RV.
All the cuts outs for plumping, electrical, tank hookups, etc on the RV are usually cut larger than needed and the manufacturer does NOT put anything around the openings. This is common on ALL RV's.
That is how the mosquitoes get inside your RV also.
"Just One Bite" is IMHO the only stuff to use to get rid of mice. I would only use this stuff in your storage area away from pets and kids. But it does the job.
I bought a can of "Stuff" and sprayed it on all the openings. Easy and fills the hole tight.....no more critters or bugs.