LOL! I like the rat idea best - sounds like true justice - get a rat to get rid of the mouse! But what if they decide they like the wild life better than coming back to you? Now you have replaced the tiny cute little mice with HUGE ugly "mice"!
Second best suggestion is taking that electronic repeller into a pet store to try it out! I want to be there - just the thought of that is hilarious! But it is true - none of those electronic things, for insects either, have seemed to work for me.
Seriously, although cleaning helps, as in the examples above, rodents will eat many things, including your linens and clothing and especially wiring and insulation
... so it is critical to eliminate them before they munch up a repair bill for you.
I owned a couple of small beach motels for a while, and the mouse and rat problem required constant diligence. First line of defence is close all entry points
that you can find. Appliance vents, the holes for your power cord and hoses, roof vents - block or screen them all.
I would never recommend using poison of any kind INSIDE. Outside is fine, but if that rodent hangs around nibbling on things, he could very well crawl into a wall or ceiling and die. The stench of that decomposing is horendous. My brother had to rip out an entire wall to remove the rotting carcass of a poisoned critter. And even worse, if you are not around and it rots in your MH, it can take months to get rid of the smell.
Our most effective solution turned out to be the cheap, old fashioned mouse and rat traps. And peanut butter seemed to be the preferred bait. As stated earlier, do NOT put them inside and draw them in. Put them outside the MH. On top of the wheels is good, but also put a few around the perimeter - never hurts to draw them AWAY from the MH. Put some near where they actually enter the storage area.
Check the traps frequently - you can't catch one if there is already a dead one in the trap. We ran a trap line of about a dozen traps and checked them twice a day, caught a bunch, and after about 3 weeks pretty much cleaned out the neighborhood!
You CAN prevail! LOL Good luck!