Current house is 2500 sqFt 4 bed 2.5 baths. 

I thought you were building to sell.

I’m able to pay cash for some houses occasionally when my savings builds up.

Raise the $600K, do the pre-development work, then “sell” the property to NewCo.  

I do this by doing open house showings.

Now, I’m rebuilding my portfolio while continuing to help others buy and sell homes.

I'm looking to do a third house hack/BRRRR in the next 2 years.

Also seems like a lot of MF sells occupied with tenants in place so you just have to comfortable with that and contracting up from and seeing inside after contracting.    1st step is to find a great lender and get pre-approved for a loan so you know what your budget is. 

Another option is to sell one or two of them to pay off your LOC and then keep just one.

I considered starting out house hacking a MF, but it will only increase my monthly expenses, not lower them or provide cash flow.