I am an accredited investor, looking to invest 50k to start since it’s my first one, and predominately interested in multifamily as my only previous experience is a rental I manage on Airbnb.

In order to get there it would be good if you could keep feeding cashflow proceeds back into acquisitions, on top of your continued W2.Speaking from experience, you can manage probably 30-50 units yourself nights and weekends before you really need to hire someone.

Sounds like for now the idea of eventually selling the branded account is a no-go, but there still remains pros/cons on each option and I'd love to hear what others have considered or their experience in adding more STRs/boutique hotel type properties to their portfolios.

It generally isn't worth the brain damage of experimenting though....especially if you want to move to a new home that you will own inside of the typical lender's seasoning period.

You'll maximize your returns from doing the complete project as well as a great learning experience!

Also, how do you factor or account for an area/town that experiences lots of seasonal tourism, compared to the town that does not? 

The below is not legal advice and you should hire a lawyer with past subject to experience. 

You’ve gained valuable experience from your first duplex and are now approaching real estate with a strategic mindset

From personal experience, I would recommend Tulsa or Oklahoma City.

Most of the lenders I work with (provided you have experience and a credit score over 660) would do up to 85% of the purchase price and up to 100% of the rehab costs, provided this doesn't exceed 75% of the ARV.As for the idea of selling the land, great idea.