From my experience, Aircover has been covering loss of income if there were bookings for those days. 

@Raul Velazquez The 3 things I would recommend besides reading books/audio/sites are:1.

I also like the strategies outlined in Brandon Turner's "Rental Property Investing" book.  

Just make sure you are saving towards those slow months during the peak months, buy a deal at the right price (don't overpay just because its a turnkey STR or you think it will make more money than projected), and look into ways to increase bookings during those slow months with some marketing and operation tweaks. 

Zoho Books, I am not using this as my partner uses it integrates nicely with CRM for book keeping and I could provide access to our CPA for Taxes. 

It stays booked in the summer and is quiet in winter (cannot use the lake, community pool, community golf course, etc).

Read my book.2.

I was just reading Mark's book "The Tax & Legal Playbook" this morning and it specifically had a "critical warning" (page 31&32 in Chapter 3).

Best bet would be disclose in your listing & disclose again in your welcome message when they book.

Do you have any books or resources out there that he can dive into to help him hopefully avoids some of the common pitfalls?