.- You mentioned this sale is tax free 121 exclusion, which is great, and seems like a solid start to your goal.- The townhouse you're moving into is currently a rental, but you plan to live there two years for the 121 exclusion.

If you do find that the costs to maintain the investment property are too substantial and you'd rather sell down the road, it would qualify for a 1031 exchange since the property was held for investment use.

With an SDIRA, you can invest in long-term rentals while preserving your retirement savings, but you must follow strict IRS rules:1.

Regarding getting started, I recommend finding an STR owner who's overwhelmed or just worn out with managing their property, and perhaps who's also not using a dynamic pricing tool, and then offering to manage it for a very small cost. 

Some things are more important than others--so those are where you invest time.

Personally, I advocate for a long-term investment strategy and would recommend investing the funds, provided you are comfortable with the expected return on investment over time.

How long ago did you start? 

It’s really amazing to see you getting started in real estate at such a young age and Out-of-state multifamily investments are a great way to begin. 

its unfortunately not going to be as easy as googling, but that might get you a list to start with and refine.  

As a starting point: -If they work full time and make $700k a year -Don't want to or can't spend time self managing a short-term rental -Don't have a spouse who wants to take the lead on managing the rentals They are likely not going to directly reduce their taxable income with real estate year-to-year.