It now makes me question whether other platforms, like Avail, are also allowing the tenant to pay via credit card and we as landlords are just unaware of the mechanism because it's a side of the transaction we don't have visibility into.

I disagree, I had a time when my name and the name on the insurance didn't match and the lender was all over it, regardless of the on-time payments.Your best bet is to refi into a commercial loan that allows the LLC (if you've already purchased the property), or close directly with a commercial loan / DSCR loan.

Out-of-state real estate investing could be a good option, as it allows you to leverage your capital without the day-to-day hands-on work.

Tons of jobs and growth which allow for better tenant selection, low crime/safe, etc.

Then what I would likely do is use self leveling concrete to make the surface level and flat.

Allowing them to pay it off early and use the cash to buy another home. 

FHA also allows some flexibility with grants and assistance programs, which could help with closing costs or down payment.

I decided to open a HELOC on my primary residence, this allowed me to have access to capital if I came across an available deal.

Do not just allow one person to keep an eye/contact the city.

Lenders also have interest only options that could help with cashflow especially on acquisitions to allow you to get the listing up, and have your listing gain momentum (some listings start off slow while they accrue bookings, reviews, etc.)