The limit on scaling is your deal flow (mine never was that good) and time it takes to perform the value add (I got fairly quick for example, my last rehab did all new plumbing, electrical, and flooring.  

Talk to other clients, go look at his current job site and see how clean it is, the quality of work, if the order of operations is making sense so far, etc.PS I'm a GC in the Nashville area and can take on a handful of clients in 2025 if you need me.

Renting out a room is a great way to get started, and I wouldn't get too settled into the "going rate" use that almost as a floor. 

The truth is, they will keep playing games and milk you for every penny they can, then they will leave the house a mess and cost more with cleaning, repairs, and vacancy.

Its like the Airbnb that says $20 a night but when you click its $100 cleaning fee. 

Best way to find end buyers is to ensure it's well marketed - Professional photos, professional clean prior to listing, aggressive list pricing.

LL would have no incentive to paint, update flooring, etc.  

Marble counter tops, textured floor, etc on theinside.

Just be the absolute best host you can be for the first year -- communicate clearly and quickly, make sure cleaning is top-notch, make sure all amenities work (hot tub is hot, TV remotes have batteries, etc. etc.)

For example, the 2nd to last photo of a random wall and floor with part of open door; what is that supposed to be telling?