Thanks, @Greg Scott, I really appreciate your thoughts on my post. You gave me important points to consider.
I am not sure how to determine the ARV. I bet someone has posted about that though. I'll look into it.
I think the struggle I am having here, is that I want this property to work as an investment, but because it is the neighboring property, I have ulterior motives. Really, I'd like the house to be an airbnb, so that: we don't have a full time neighbor that close, I can have a project (I enjoy decorating, cleaning and meeting new people), and so that I can have the freedom to use it as a guest house for friends and family visiting. Eventually, if I don't want the hassle of managing an airbnb, I can turn it into a normal rental. So, I guess, my thought process on this property isn't so much as an investor trying to get the highest return on my asset, but first rather as homeowner wanting to absorb and control the hillside and secondly as an investor.
Never the less, I will do the math like an investor as you suggested. That makes perfect sense to me. And I think, like you said, just being honest with my neighbor from the get go, allows her to know where I am coming from and gives her the freedom to put it on the mrket should she require a higher price.