I'm not sure if the program is still going on, but has definitely revitalized a lot of the area when it was once destined to follow the way of other older cities that are aging out of existence both in terms of people and property. 

However, Opportunity Zone investments require careful structuring to ensure compliance.Evaluate your priorities: If starting a business is the main goal, proceeds from your primary residence (with the capital gains exclusion) might provide the simplest funding option.This post does not create a CPA-Client relationship.

I believe Alexandria city allows it but portions of Fairfax county do not allow it. i would go option 1 personally. 

I've read BiggerPockets' Real Estate Investing book and am particularly interested in the house hacking strategy, as I'd like to move out of my current living situation.Our main dilemma is choosing between a single-family home (renting out one room to a close friend) or a multifamily property like a duplex or triplex.

The logistics are simpler since as you get 4-5 turns/year and it isn't affected by the city ordinance on STRs.

If you're in real estate, whether as an agent or a developer, SB-9 in San Diego City is something you need to have on your radar and smart investors can make it work to their advantage.

As long as the property cash flows, that's what is mainly needed. 

My main goal is it be able to retire at age 40 from my main job and work entirely on my real estate portfolio.

The main reason is that it is not initially set up for a Real Estate business like other “real estate-specific” accounting software.

But from my understanding, the captial gains exclusion has two main criterias - you must have owned the home in the last 2 to 5 years and must have lived in the home in the last 2 to 5 years.