luxury portable toilet rental I heard has good cash flow for business.

We have about $250k in equity, its only cash flowing about $200 after expenses, but our loan is only at 2.375%.

You should review the comps and cash flow predictions to make sure you're hitting your metrics. 3.

He also wanted me to look into areas where my investment cash flows well enough to dig deeper into the real estate market than spend all my savings on one property that barely cash flows. 

Chasing cash flow in these neighborhoods is rarely a viable business model as I've learned.

Then down the road as you raise rents and you find yourself cash flowing.

The renovation will convert a row single family home into 3 family home ( the layout is already there ):- the first flow will be 1 bed, 1 bath- the second floor will be 2b, 1bath- the basement.If those 3 rents, I can easily have $1800-$2000 in gross rent per month.So any creative financial idea I can propose to him?

Here's a guide that describes what good cash flow looks like and how to analyze a property.https://www.biggerpockets.com/blog/rental-property-cash-flow...  

Reno is considerably less expensive as an entry point compared to CA. 

Even if the borrower doesn't have the best credit, as long as the property has good cash flow and down payment, they'll fund it.