Lots of maintenance and cleaning.

Are the tenants units clean and taken care of?

I would also advise that you keep an emergency stash of cash in your regular bank.

If you have a clean file my LO can close 10-14 days after going under contract.Data for July indicates that we are seeing increased days on market, increased active listings, and will likely see increased new listings, so your agent should be able to find a solid house hack option in the Denver area within 2-4 weeks. 

I would figure out how to remove the tenant, clean the place up, and sell it.

They are regularly getting poor valuations compared to the cost to add the ADU.   

My wife and I cleaned out eviction properties. 

From there it's your regular ol' cash on cash return calculations!

Consider the additional costs for cleaning and maintenance with Airbnb.

Would you still use your friend as your GC and just pay him his regular rate (and would they be happy about the new arrangement)?