An optimal BRRRR really requires that you purchase with cash (or something cash-like) and not conventional financing. 

.)$59,500 cash TO YOU at closing.Option 4 (cash out)$375,000 loan amount4.125% Fixed30 year conventional$10554 loan costs (1.75 pts/$6,562.5)$2009 new monthly payment (including your taxes and insurance.)$61,272 cash TO YOU at closing.

My intention was to do either a 3% conventional or 3.5% FHA loan-I have a low cash down payment that I have raised. 

@Pete AbillaIf your credit score and DTI qualify, then you can get 5 mortgages, even conventional, and close simultaneously.

Most loans out there are convention / conforming loans that conform to Fannie Mae / Freddie Mac guidelines.  

In the event of seeking financing through a conventional mortgage in the future, on new large purchases, I’m wondering if we need to disclose the mixed use land contract if we also aren’t disclosing the income from it?

We did a conventional 30yr fixed rate loan. 

We financed the home originally through a conventional loan with a local bank.

You'll have a tough time getting a low-down payment conventional loan that will roll in renovation costs.

Or work differently so you produce a greater income and can buy all cash (or pay down debt so you can get a conventional mortgage)in your question I hear you wanting to be creative, which is awesome - however creative in looking for money means you may want to go where there is money?