I have enough cash flow with multiple paid properties but just want to ensure I’m not really doing something strange.

Use a reputable company to help you ensure it is done well, like Corporate Direct. 

I plan on doing 203k to ensure I have equity, and HELOC it after another year of primary residence to have enough to put 20% down on my first investment property.

This is of course assuming that you have a solid plan to ensure that you're successfully able to get out of the hard money in time, etc, and weather any issues until that point.

Is there a good strategy to most efficiently pull about 75k out to buy some SFH?

Get this right and buy good properties that you can get tenants that can pass a high standard tenant screening, will help ensure you will NOT encounter too many bumps in your road to achieve equity growth.Lastly, I did rent to one of my brothers, but I had explained to them that it's a business.

I'm not opposed to S8, however I would want to ensure the tenant still meets my criteria.I agree, credit scores do not tell the entire story and an established employment history with a good employer reference usually does the trick. 

How did you ensure occupancy rate was high enough to keep the investment profitable?

However if you are in a market that you believe will appreciate in the next few years a 1031 exchange will mean you miss out on the appreciation.Option 2: Do the cash out refi for 60% LTV to ensure you have a cash flowing property.

You used a private loan to ensure you didn’t lose a deal?