Add and ADU to and existing Duplex Property?

[John B.]

Hi Everyone - Looking for general short-term rental / ADU advice here.

I currently own a duplex where I live in one unit and short-term rent the other. I make about 45k/yr just off that one unit via AirBnB. I have a small property, but for about $150k I could build an additional unit and probably make another 30-40k/yr off of that given the area I live.

Here are some numbers: Purchased house several years ago for 550k. Have about 400k left on mortgage. Property is current worth about 750k.

Seems like a good investment to me, but I worry about over-leveraging in a hot market if I decide to sell at some point. What are your thoughts?