Most recently a tenant moved out and left the house full of roaches and another one just had an animal in the attic that somehow knocked down the ceiling light in the kitchen.

I've been on the LL diaries podcast and am not knocking other hosts but keep in mind that a lot of hosts entered into the market in 2020 or earlier where rental rates in the Sunbelt markets like Nashville, Austin, Houston, Charlotte, etc. had very low rent rates.

We haven't had big parties or anything like that or destructive guests (knock on wood).

So I’ve since blocked off the third floor on one side and rented it as a 1 BR for now. but when the other side leaves eventually I’m starting to lean towards raising the ground grade 28” so that the total drop is less than 20’and then I’ll knock down some walls and make the whole 3rd floor attached only to that last unit so that the whole area can use the stairs and that window as second egress. 

so if you just buy a random property with 100% financing, you'll never pay back the loans with the property - you'll be negative and  have to pay it back with other money.and if you BRRRR using 100% borrowed money you have to really knock it out of the park to get all your money back, which is very difficult to do as a new investor.the way BRRRR works (as you know) is you buy (with money - cash from your checking account, cash from your uncle, hard money, a HELOC, a cm) fix the property up, then refinance. 

(Call, text, door knock until they give you business.)

Have them pay for it and you can knock it off first month's rent if you wish.

On several occasions, when I’ve noticed the tenant's car parked on the property, I’ve gone over and knocked on the door, but she hasn’t answered.

If you can't evict tenants to knock down a property, and/or remodel it, or otherwise improve the property... you won't. 

If Planning does determine the existence of your ground floor unit, it will require you to legalize the unit through the existing Planning code process assuming zoning supports the third unit OR using the new ADU program making your fast track condo conversion a passing dream.With regards, to some of your latter comments and questions:1) Any un-permitted work (including corrections) is not a good idea as a quick compliant from a neighbor can bring an inspector knocking on your door with a NOV especially in the current environment where everyone is SIP.2) Legalizing existing constructed spaces can be hit and miss based on the inspector you get.