I'm a 2x house hacker here in LA (a case study in the BP book The House Hacking Strategy) and an out of state investor.

With your costs being less you can invest more into the property to build reviews and get bookings. 

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

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. 

But if anyone can recommend a book, a podcast, a youtube on how to start in AirBNB will be so much appreciated.

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

If my crystal ball is correct, we are going to see a lot of these sub2 deals hit the fan in the next 36 months. 

You could check out a book by Dave Van Horn called Real Estate Note Investing.

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. 

@Michael BaumEvery property we ever stayed at had a physical book so yes - it definitely suffices.