If you have insurance, generally, there is mold remediation coverage. 

What is on the insurance application that you signed? 

Credit is a factor as bad credit may limit options, or may have the lender require you to put 10 or 20 years of taxes and insurance into escrow. 

This property was in rough shape, so I tackled the essentials: new roof, plumbing fixes, and updating the interior to make it livable again.

We are about to put in $15-$20k of our own money into it, beyond what insurance covered and I need help deciding how we should finance it. 

That's $1,600 per month plus to pay debt, plus at least $400 in taxes and insurance.

Electrical work, plumbing, foundation, windows, roofing, and AC/Heat.

I think your biggest issue with any "work-arounds" is going to be your legal liability and holding the proper insurance in case something goes wrong, which I'm going to assume you'd need to be properly licensed in order to be properly covered by insurance.

A good property manager can help with tenant screening, enforce lease terms, and handle evictions more efficiently if it comes to that.Require a Larger Security Deposit: Within the bounds of local regulations, a larger deposit can provide a cushion in case of damage or unpaid rent.Consider Rent Guarantee Insurance: Some companies offer insurance products that can cover lost rent in case of tenant default.

Quote from @Cody Caswell: Quote from @Jay Hurst: Quote from @Cody Caswell: Is it true you can use taxes, depreciation, insurance, and mortgage interest for qualifying income when applying for an FHA loan on a primary residence?