Our storage has been outside on a farm, with around 20 other vans. The guy gave me the opportunity to move it inside last week in a barn with 3 other vans.
We took him up on the offer, as had been having a nightmare getting the van into our allocated bay in the compound, plus figured it would be far better for the van to be inside during the winter.
Now I'm wondering if I need to do anything to protect the van from mice or anything?
if its a working farm like here get a cover for it, as there is a lot more dust inside a barn than you may think, but in general you are no more at risk from mice than anywhere else. if they are about get a sonic repeller and that will help in part with keeping them out. but its not 100% a cheap cover will cost around £40 and more than pay for its self. beware of the grey cloth type if you leave the cover in the barn when away as mice love it when rolled up. ensure it goes into a box or bag safe and away from the buggers, and not as I did just rolled up and left in a corner.
yes your unit will be better off being out of the rain snow and frost. and a bit safer.
We have stored ours in two different barns on two farms and never had trouble with mice but the van did seem to get very dusty, did not bother me as I always washed it when we got it home or to site anyway. But if you can't do that you may want to invest in a cover.
It's not a fully working farm, the only livestock I have seen around is horses. The van was getting dusty outside in the compound, as it is very open and you could see the dust blowing off the fields, so it is no worse off inside. We are generally away every other weekend, and the van will be getting cleaned when we are on-site so sounds like we made the right choice.
Before we moved to our current home, we stored our van in a friendly farmers disused barn; now kept on the drive. The main difference I notice is the roof used to stay clean! Would only need to wash roof once a year, now have to do it several times a year. Still prefer it on the drive though. Use one of these to wash the roof: