If I were a mouse, I'd want to get in our warmer than outside and cozy RVs during the winter too. We block all the entry points, remove all food and do a good cleaning like all of you guys.
Something I have not heard, we remove all dish clothes that have any food smell in them. As well, we remove linens and soap cause mice have nibbled on our soap in the past.
Then, sorry "PETA", I put rodent bait (rat/mouse poison) in multiple places inside and outside the FW in the shed. BE VERY CAREFUL TO PLACE WHERE PETS CAN'T GET TO IT.
We also place the old standard mouse traps everywhere. I use the weather proof type that will not mold from Tractor Supply. Tomcat® All-Weather Bait Chunx, 4 lb. Pail of 1 oz. Chunx - Tractor Supply Co.
If all else fails, I find a big ole black snake and turn him loose in the FW. JUST KIDDING! We did gave a black snake get in an old worn out and holey 1972 Winnebago one time looking for an easy meal in the early spring. As you can imagine my wife made me tear the RV apart before she would go in it.