It will likely depend more on the property's debt service coverage ratio than on an arbitrary percentage. 

My Contractor an I visited both properties and he provided the quote for services and materials.

Also, it creates value as properties are improved and a service is offered.

Has anyone done AirBnb before and, if so, how did you handle cleaning and maintenance? 

When I see it the amount is 12-15% but I see people in your position utilize that huge equity as an easy way to get private short term money from friends and family and then clean it up on your cash out refinance on the new property.At the same time look at your cost you pay for the existing loan vs a refinance. 

How much are you planning to borrow and will the new actual income adequately service that debt.

Once you figure out exactly what they are doing or how they structure these it would be a nice service to post about the actual set up .. 

In addition, solar requires monitoring to ensure that it is working fine and the solar panels need cleaning every few months. 

"either keep this place clean or all of you are getting 30 days notice.

I guess we can do a walk through and discuss the price in advance, what are the rules of thumb for figuring out a fair price for repairs, cleaning, maintenance etc. ?