On my TT I bought a kit from Camping World and switched the pull out power cord to a removable one. I have heard of mice coming in that way but have of ants. The make a pest detergent expanding foam that you could use under the tub.
For me the best Mouse Traps are the snap ones. I tie short string to the trigger and rub peanut butter into the string.
TV: 2013 F350, Lariat, 4x4, CC, LB, 6.7L Powerstroke
FW: 2013 Jayco Eagle Premier 361 REQS
Additions: Onan 5500W LP Generator, Surge Guard TS,
.......Roof Satellite Dish, Vent Covers, Bedroom Vent Fan,
.......Rear Reciever, 12V DC Outlets (6), 320W Solar & Controller,
.......4 Lifeline AGM Batteries (600 Ah @ 12V),
.......Stereo Upgraded, Interior Speaker Upgrade, Amp