since you are not going to be towing much and will be under cover, you would not have to buy what is considered a full timer unit. these units are more expensive and a good vacation unit would suit your needs. with several family members, you might want to get the longest unit that meets your needs as you will need storage and space. will you need washer dryer? make sure the closets are deep enough that hangers do not having to be turned to get the door closed. will the barn be ventillated enough if you need to use propane appliances or furnace? if you are parking on a concrete floor, i was told to put something under the tires as the concrete will draw the moisture out and cause them to rot. i see and have heard a lot of good about montana units.