Unfortunately, if you go with conventional, even with a co-signer I don't think they'll allow you to qualify without that money being seasoned.I do think there's a red flag there with what you're proposing.

After some time I became a co-host of his homes, and then gradually took over all aspect of his bookings, repairs, coordinating of cleanings, guest communications, etc. 

I'm a co-host in the sierra nevadas and happy to answer questions you have. 

If you’re a busy Airbnb host who needs a break from the daily grind of guest communication and check-ins, why not consider adding a co-host to your listing?

First, there usually isn't a cos section for an operating building only for contractors and developers who are selling properties.

I asked a co-habitant to vacate.  

I’d suggest bringing in an equity partner or having a co-signer on the loan.

In order to get a conforming, low interest, 30-year arm loan we will need a co-signer (we don't have regular income).

Any landlord seeking to convert to a co-op or condominium must file appropriate notification with the Rent Leveling Board.

For example, William Shockley was a co-inventor of the transistor (smartphones would not work without them) and a proponent of eugenics.