The appealing aspect here is the ongoing population growth and other economic factors.

You see people add basement "rentals" fairly consistently.  

For illustration purposes a quad consisting of all one bed one bath units will cost a lot less to build than a quad consisting of all 3 bed 3 bath units.....

Overall, I learned there are many aspect sand parts in a Flip: from Realtor, City Inspector, City Code, Contractor, Designer etc.

You may have a grasp on this aspect, but there are items to consider that can play a big factor when choosing your land such as topography, existing zoning & platted lot status, minimum/maximum requirements such as parking, detention, size of building, setbacks.  

Learn how to hit singles consistently.

I think just reading books, being active on the BP forums and consistently attending your local REIA will be more effective and far cheaper. 

The plus side is once you get going it's very beneficial as you should have consistent bookings.

EXAMPLE: your wasp nestAlso, as you've learned, no one person is consistently going to your property and keeping tabs on it. 

I've talked to many clients and investors who consistently lose over 10K per year on MN Cabin STRs.