I’ve done a couple of fix-and-flip projects in the past, both of which were financed through hard money lenders.

Whether you should take a retirement distribution or not depends on several factors1) How much do you value the freedom/flexibility to ues the money NOW compared to when you are 60 years old.2) What type of return can you get having cash vs investing in an IRA / SDIRA.If you can make a 1% - 2% better annual return in your personal name, it may make sense as the added return will pay for the penalties over a couple of years.I personally cashed out of my retirement account back in 2016 and it was the best decision I made.

ChatGPT gave me a couple of recommendations on that. 

A couple of questions about determining the ratio of units to population.   

I manage around 400 rentals and probably terminate a couple dozen every year for lease violations.

Neighborhoods can change in a couple blocks. 

Here in Detroit you can buy a couple of properties for $250,000 cash.

No way to say for sure since each lender is different and I have no idea of the terms you need or your FICO, but it is typically the prime rate plus a couple of points.

I had a couple clients lock in just recently at 7.1% on 10-30 unit deals.

As a couple others said emergency would negate the $500 threshold but they should contact you to notify when it happens.