We are planning on purchasing land in Sevier County, Tennessee, with the intention of setting up a mobile home and then renting it out on Airbnb. The lot has A-1 zoning. Is this legal?
It's not impossible. Here are the regulations. Single- and two-family dwellings are legal, as are mobile homes. But the activity is not necessarily allowed (since you aren't residing there). "Customary home occupations" are allowed, but that means businesses customarily run out of a home like making / selling homemade arts & crafts, selling antiques, education, but also "Any other uses which the Board of Zoning Appeals finds to be of similar character". However, "Public Uses" are allowed with an approved site plan, spelled out in §303; or "Rural businesses" with similar approved plan. This means you have to give lots of information about the site and the plan has to be approved. There doesn't seem to be a specific prohibition, and the use seems consistent with the principle that
This district is created to establish and preserve areas with agricultural and rural qualities by allowing for traditional Agricultural Uses along with low-density residential activities
but the Sevier County Board of Zoning Appeals might feel otherwise. A counter-indication is that §504.3.1 lists for R-2M zones "Bed and Breakfast Inns, limited to a maximum of four (4) bedrooms for rent", thus the zone must be more residential for B&B usage to be accepted.
Since the standards are not clear, the only solution is to officially inquire with the Zoning Board.