They are still paying but very late each month, so I'm afraid of them becoming no-pay tenants down the road. 

Just pay another agent to show on your behalf - easy.Here is the ironic piece.

Should I require both of them to pay application fee or only one fee?

If you do pull out money from the HELOC, have a plan to pay it back within 18 months.

Obviously, if the tenants fail to timely pay rent, you can enforce their obligations with a notice to pay.Your question is legal in nature, so I recommend that you consult your landlord or FHA attorney in your state about it.

I am, like a number of the folks here, looking of a product where I can run  mulitple business in one product. 

s mentioned JV is best initially ..always pays to be circumspect and cautious the first few, once you gain confidence all alone is good to go!!

I'd reach out to someone in a local REIA where the property is located- those folks will know of some private individuals that are looking to lend. if the SFH is your primary residence, you should be able to get a HELOC at a decent rate from a regional or credit union.

BRRR deal could get you the cashflow and the value add payout without having to pay capital gains on the equity.If you’re not fatalist with the Multifamily Wealth podcast with Axel Ragnarson I’d highly suggest checking it out.

They say the next door neighbor was renting it (stop paying) for storage and continues to use it.