I wish I could be better help on specifics, but this is just the start of the process.

Just like Kevin, I start out by using the 5/5/5 rule of thumb.

However, it’s time we start recognizing them for what they truly are: an affordable housing option for those who want to live independently on a budget.Rooming houses provide a vital solution in today's housing market, offering flexibility and affordability.

This just might be my opinion but at this point even if you're out one months rent which definitely sucks it may just be easier to start showings.I don't know what the L/T laws are in your county/state but perhaps send a notice to the emergency contact with something to the effect of pay or quit with an option for a release out of the lease and be done with it. turn over this unit and get it out on the market again.

If you are starting out, I would hire a property manager to manage for you.

Wow that’s an awesome some portfolio you’ve started amazing. 

Quote from @Donna Brake: Start the eviction process on the earliest date allowed by the law and your lease.

But that's a fair starting point. 

Also, the roof is a barn-style roof, so it starts to slope at about 4ft high.Is there anything I should add or change to suit MTR (and STR in the gaps of no MTR guests)?

Welcome to BiggerPockets Isaac and good luck getting started!