There are opportunities out there but some strategies are risky. 1 - Airbnb (STR) comes to mind - very competitive, very saturated and becoming highly regulated.2 - Most STRs are transitioning to MTR so that market will be saturated soon if it isn't already.3 - Insurance crisis in florida is getting bad so those costs will eat up cashflow and short term appreciation.

Take out an equity line of credit on the property that can be sides as the down payment for the primary residence.

I think the big question is how badly do you want to keep the extra $50k liquid?

no one killed that we know of so far but several injuries and a few neighborhoods hit pretty badly. 

Criminal background will weed out some bad actors as well.  

On the flip side, if you've got a bunch of Section 8 tenants living in a building that's in a neighborhood where a lot of the tenant base has good jobs, high credit scores, and are generally reliable people, you've got the most risky tenants in that tenant base and that ain't what ya want.

Meet with a local banker & schedule a time to talk with a mortgage broker, they'll give you at least a baseline of what kind of down payment options and rates are out there.After that, if you're still wanting to research more creative options, do some looking into seller financing (a very hot topic with good, and bad, advice out there), look into private lenders, and commercial financing options.If you're wanting to live in 1/4 of your quadplex, then conventional residential loans may in fact be your best option as you can purchase that with a fannie/freddy loan with very low down, and use up to 75% of the income from the property toward your own income. 

Rates are hovering in the mid 7s depending on your credit score.

(It costs 10k+ to drain, clean, refill the pool so I only do it once an year and this is pretty standard) I think it is matter of if it looks dirty or smells bad when guests use it.

What documents do they require, what credit scores do they allow, how do they verify previous rental history, etc.?