An overlay is an additional guideline that a lender has imposed on top of Fannie/Freddie Guidelines, or USDA/FHA/VA guidelines. 

Read up on fair housing screening guidelines and follow them to a "T."

That is gambling so be cautious.

I’m going to want to check the guidelines with Covid to see if anything‘s changed in the last month or so

I know most municipalities here in CT have those guidelines.

Debt ratio is debt ratio, but the guidelines only allow 75% of the rents to wash the mortgage, so there's a potential, if the cash flow isn't significant, the new debt may be counted against you. 

Meaning that, there are no standard (Fannie/Freddie) guidelines or rules for them. 

Lender's are now slowly rolling back their recently tightened guidelines, but everone is still have some extra 'reserve' requirement, slightly lower LTVs (in many cases - some are back to pre-COVID) etc.

Or you can just put all All of the income from the property back into the line of credit for payment .This is tricky because they're really not any terms for us to look at numbers Etc to tell you and say hey this is going to be tricky this is going to be easy and this one's a Gamble.

Local banks are great but can be very picky with retail guide lines and overlays.