Opportunity zones is another way to offset capital gains tax.

Congrats on this investment @Glen Gaines ! 

@Glen Gaines, welcome to the BP community

Would it need to be done to where only 2/3 of the sale of the second property's earnings is "shielded" from capital gains?

House-hacking a multi-family property will allow you to get in with as little as 3.5% down, gain acquisition/ experience AND get you started as a RE investor. 

You could potentially take the gains and use that to purchase several more properties, or a larger multi-family to get more than the $300 monthly cash flow.

Disadvantages.....1) inheriting possible liabilities2) you also acquire the current, depreciated basis of the real property (not the price you are paying foe the llc) which will affect your depreciation and capital gains when you sell the property.

Thoughts on buying more rentals (with loaned funds) to offset gains on other rentals???

Get in touch with your local real estate investor networking groups and start gaining access to off market deals.

Not sure what unit count you're considering but the nice thing about jumping above 4 units is the bank will put more weight on the performance of the property than your own personal finances.