Remember you will have to maintain the license and do continuing education to keep the license active.

Alternatively, you could continue to hold and rent them out assuming that they are cash flowing well and either do a cash-out refi (preferable for your next buy/hold) or a Heloc (preferable for fix/flip or value add purchase) and utilize some of the equity to increase your holdings.

I’m looking to make the duplex a full rental property and continue my investing journey with it.

They also continue your depreciation schedule.  

Now, I expect to continually grow my income over time, even in retirement, and will be taxed higher than I am today, which ironically, creates a desire to leave my W2 so I can access the 401k balance sooner rather than later.  

Continue to watch your investment grow and repeat the process with larger apartment complexes.

Instead of continuing to build up my real estate portfolio in small multifamily (1 - 4 units),I am now leaning more towards Syndication and possibly Triple Net Lease opportunities. 

I hope that he continues to stay renting from me.

Aloha,Simple answer: it depends.It depend on zoning, it depend on NCU (you can find out if your unit currently has valid certificate), it depend on condo’s by-laws and house rules (it will continue to change).Honolulu City and Council is currently tabled several bills to regulate and taxed, we won’t know which bill passes, or continue to amend and when the bill into effect.https://www.google.co.jp/amp/s/amp.thestate.com/news/business/national-business/article229502899.html

You may want to continue month-to-month in the beginning since you haven't screened them and you don't really know the type of tenant they are.