@Scott Tennell there might be two different definitions here to the PML term.So, if you mean you are reaching out to PML that lend money all the time and have experience doing it - then they will tell you what their requirements are.  

@Michael Nguyen I’ll share a different perspective.

Most primary residence lenders are not going to lend in second position for a purchase.

Hi Jeff,Regarding the cash out refinance after an Exchange, you are going to get different opinions based on who you ask.

@Jack SeidenGreat question: I am 60/40 stocks and real estate right now, excluding my primary (my investment in BiggerPockets as a private business). 

i think selling to other investors would solve some of this, as i believe the same rules do not apply to rentals as to primary residences. 

If the duplex sells for $500K and you exchange into a duplex in LA for $1 mil then you could use 50% of it as your primary residence.- Do I qualify for for a section 121 exclusion sense I lived on the property for the first 2 years of ownership?

Read every book you can on different niches of investing, at least one per month.

Pete Beach has varying STR rules in different areas, and each condo HOA sets it's own stipulation on 3, 7, 14, 30+ day minimums.

If it was me...I'd check with zoning to find out how many dwelling units I could build, and I'd find what the requirements are for those units (type of house, height and setback restrictions, etc.).Then I'd find out what local builders think the cost to construct would be - just get a cost estimate per square foot for 2 or 3 different levels of finish.