They offer various loan terms and competitive interest rates.

Sometimes control can be more advantageous than ownership.With the terms locked in place my plan was to sublet the lease option.  

After leases expire, landlords can draft new leases, re-negotiate terms, adjust rent, and implement policies.

Unless you have an HOA that does not allow for short term rentals.

What is your short term plan for the TN house?

Term 12 months or less.

For those in the highest tier (or know about it), can you give a general description/example of how the process goes in terms of if you have to fill out a lot of forms in order to invest in properties (and if so approximately how many) and what amount of time you spend a week on your investments?

It's more straight forward to replace faucets, sinks, light fixtures, etc, all of which can typically be done without a permit.Only homeowners working on their own owner-occupied home are excepted from the requirement that a permit be pulled by a licensed builder - but even then the homeowner *does* have to pull the required permit.

A DSCR loan or HELOC for purchasing another mid-term rental?

Of course, it ultimately depends on your available funds, short/long-term goals, etc.