Look for multis with separate entrances in different areas like one door in front for one unit and a door on the side or back for another.

Does the side unit have a separate entrance like a mother-daughter? 

Like @Russell Brazil said there are general things that need to be in place.One that stings a lot of people is the main entrance door.

I'll include all details below.THE LOCATION: The hotel is conveniently located in the breathtaking Smoky Mountains, just minutes away from the Great Smoky Mountain NP entrance.

We were actually named the 4th Best Place to Work in America (small employer) {https://bestcompaniesgroup.com/americas-best-workplaces-awar...}.

They sealed the entrances using metal screens (one around a pipe), but now the areas look unsightly.Additionally, there’s ongoing construction in the condo complex, which may have driven the mice into my unit.

I do think you need a separate entrance option or at least two entrances in a four-plex to make it easier on the LTR tenants, but if you are open about it form the start, everyone gets it and you choose the unit composition based on which ones will be STR or MTR.

Everything suddenly makes a loud & notable entrance.  

@Hamidou Keita I would recommend if duplexes are limited if you can get a 4-5 bedroom house and either rent by room for house hack or splitting a big house into 2 and adding a kitchenette and separate entrance as a more cost effective ROI option 

I would like to use this life adjustment as a catalyst for my entrance into real-estate.