Next day another person calls in, just repeating what I said the day before in a dumb way and eventually said, you know you have to refinance the 1st mortgage, right?

@Samuel Olivas From personal experience you can't have your cake and eat it too. 

They are business credit cards which report to different agencies than your personal credit, so it wouldn't affect your personal status at all.

If a buyer has good credit he can get a personal loan to buy a property, and hence “nothing down”.  

Personally, I'd never buy the biggest house, or the most expensive house on the street.

Quote from @David Eyal: This is actually very simple: don't get involved in personal issues.You offer them a renewal.

you mention the person who is complaining is now and living in an efficiency unit (to me that has everything in it-ie fridge, stove). 

I will say that if you get some ducks in a row, things like a good cleaner, handy person etc, you could manage from farther away if you find a deal or area you are interested in.

We took this approach because even though the house is an STR it is also one we want to use as a family a couple times per year, and we feel we have our own personality as hosts, so we were particular about what we wanted. 

I  would look at your town regulations and see also if they have any unrelated persons ordinances and what they say about boarding houses.