Primary residence gain is not taxable (to certain limits), so when you convert to investment property, you convert at a higher basis. 

You could sell the 50 units and buy say10 properties-airbnb maybe-and have that supplement your gains from the sale.

Hays county to the South, by percentage gains, is one of the fastest growing counties in Texas.

I would recommend starting with something lighter in rehab to gain experience.

Even someone who doesn't want to take a capital gains hit will not find this attractive since there is little room for a market drop. 

If the goal is to put the equity you have somewhere out of state or build a portfolio then doing a cash out refi or utilizing a heloc would be best (Depending on home much equity you gained).

One of the major elements of this, which we have not yet discussed in this thread, is his attitude on capital gains taxes.

She's newer to real estate and is documenting her journey as she amasses her rental portfolio and gains experience.

I would also consider it this way, including a picture could be seen as a strategy to gain an unfair advantage and/or bias when selecting an offer.  

There is a lot of trust involved and that is best gained through personal referrals or relationships.