Lots of great advice from people here, you came to the right place. I agree with the thought of going large for the LONG term, but you have to make sure you have sufficient reserves.
The here with large cabins with pools will continue to do well, most likely, as they can go self-contained. But we don't know what the next 2-4-8-12-24 months will look like due to the current COVID situation.
We use PriceLabs and also AirDNA. Large cabins (6+ BDRM) w/out private pools in Sevier County are only running an average of 63% booking for June/July. They also have a 51% cancellation rate (which includes future dates). Large cabins means large groups and it often only takes a couple people to back out due to a travel restriction or mandatory quarantine period for the whole reservation to fall through.
As a semi-local, I have gotten to know a lot of other, smaller PMs that have those exact experiences - larger cabins book but also cancel a lot. > 50% is a huge number. A long-time local PM, one of the better ones that was family-owned, just sold out to one of the big ones. They managed a lot of big units in Gatlinburg and just found this season to be too difficult and gave up. For those who still rely on AirBNB, it can be even worse. AirBNB will still allow last minute no-penalty 100% refund cancellations if a COVID travel restriction is in place. At the moment, 23 states have mandatory quarantines for people traveling from TN. Try filling an 8-bedroom vacancy that cancelled 3-4 days before arrival.
If governments start mandatory shutdowns again, and some nearby states (KY and IL for example) seem to be seriously considering it, large cabins will take the brunt of that. Every time a new state adds TN to the 14-day quarantine list, we get cancellations across the board. The smaller places usually rebook but notice is often too short to rebook the larger ones.
We have a 2, 3, 5, and an 8 bedroom rental. We have done a little work on the 8 bedroom that makes it easy for us to also rent as a 4-bedroom. We set it up so we could lock-off the entire lower floor without affecting amenities. That has helped us fill schedule gaps. This is a feature or capability worth looking for as you can increase occupancy and flexibility. Private pools were big this year, likely driven by COVID concerns. They will likely remain popular even after this passes.
Having ZERO bookings for the 8 bedroom from late-Feb thru late-May was a tough thing to handle but we had our reserves to fall back on. We complied with the County and City requests to not actively advertise our rentals during that time. Listings were ok, but ads, mailers, etc., were not.
Lastly, I know all local governments are seriously considering regulating pools (and elevators) on STR properties the same way they do in resort communities and hotels. I am not sure that means much. Most likely, it will require occasional inspections along with increased procedures & record keeping to ensure safe water quality. That will put more importance and reliance on the quality and thoroughness of your cleaners or pool maintenance folks.
So this was a long-winded way to simply say "be sure you have 6+ months reserves for a large cabin. They are likely the better long term investment after this COVID stuff eventually blows over."