I understand the complexity of requirements in getting 2nd home under writing. 

Large complexes don't get any value from having 1 of their units as an STR.

The question you are asking is looking to oversimplify a very complex and dynamic economic system. 

I am trying to get into the MF space. Currently, I have a few SF units, but it has been a difficult experience to find units and to connect with investors looking to sell. Ideally, I am looking for MF with 20 units or...

Let's say you own a 100 unit complex, you would typically look at the overall operating expenses divided by revenue.  

Maybe don't tell them you want to buy a 100+ complex on your own. but you may want to buy a 10-20 unit property so you want to find out what kind of terms they can offer you and what you need to give them.

Hello everyone, I'm currently looking to buy a multi-family apartment complex in Florida, and came across a land that posted as Site plan-approved development site, asking price $1.5M?

You also want to reduce maintenance and the best way to do that is reduce complexity.

I wasn't really thinking of selling initially, but a couple condos in my complex sold for over $900k, and I thought I'd take a shot to see if I could get somewhere close to that. 

Build equity and credibility, use that plus leverage to get a bigger property with my money and OPM, rinse and repeat until I’m selling smaller units and trading in for larger 50-100 unit apartment complexes.