You got bad advice from your prior accountant.You received rental income and it should have been reported.it seems like maybe he was lazy and/or doesn't understand rental concepts.The only exception is if he is paying 'under-market' for rent in which case the property would be considered personal use.I would fix the issue and charge him market rent. 

We will need to mortgage the condo or sell it in order to outfit our home (and my brother-in-laws home) for my in-laws to live privately and comfortably.

I know lumber has come down significantly and have been reading due to a slow down in the market there is over supply coming from the lumber mills. 

Just make sure your LTR tenants keep their units nice, so your STR units' market well.  

I am open to private individuals, just have not found the one who can cover this level of scale. 

Look at their marketing strategy.

There is variance in markets but I believe most high price markets are like my market with 2 primary plays 1) patience.

It's smart to invest now and be prepared for any market changes.  

Given the state of the stock market over the last few years, I'm looking for a way to invest in certificates to gain an interest rate higher than what banks are offering and returns that higher than the stock market right now.

Just state in your marketing or listing that the other side of the unit is rented out for midterm stays of 30 days or longer.