I had mouse problems for about a year.....A real mess, as you know.....I tried everything and nothing worked.....Then I got 5 of those sonic deterrents at Home Depot....Put them in the engine compartment and all around the inside of the MH.....Problem solved for the past 2 yrs.....
You will never plug all the holes that a mouse can get in.....Just too many that are not visible around corners, etc.....
The sonic things worked for me, I have heard mixed reviews from others.....