It sounds like the bathroom would be added to your primary residence so it partially depends on when you would look to sell the home or start otherwise renting it out.

Where I have rentals, it is 50-100% of the rent.

Rents on those units + additional off street parking bring in $7000/month.

The rent should completely cover my new mortgage.

Rents typically follow the "Common rents" of the neighborhood which your agent should know or have access to in most cases.

I plan to be posting in about 60 days when property is rented out. 

Hi all,I am looking at a potential rental acquisition where the home contains a garage conversion into a room and it is unpermitted.Note that seller has not included this room in the sq footage and i am not purchasing it with the assumption of conversion to permitted.If i were to buy and turn into a rental - is there any liability to renting it out with that unpermitted conversion?

Here's an easy answer for you: move into the house and rent out the rooms to generate cashflow.

Prices drive rents.

Have you looked into any rent to rent situations for STRs?