The mortgage is a long-term, fixed rate loan charging compounding interest; the HELOC is a shorter-term, variable rate line of credit charging simple interest. 

Gasoline prices have not stopped rising in recent weeks in California due to the high demand, a common phenomenon at this time of year in the state (compounded by the urgency of nearly everybody to go somewhere, anywhere, now that the pandemic is unwinding).

I’d like to find a cash flow though, without paying $20-$60K over appraised or taking a chance on Kansas... tired of bowing and scraping to sellers.

Aren't you just compounding negative CF as you grow your portfolio?

Even with a basement the walls can be cracked, bowing in, shows signs of water in the basement. 

This then becomes a compounding effect as if the next generation is smaller, that means there will be even less folks to have kids and it becomes nearly impossible to reverse the trend. 

Charge your late fees and keep them compounding until they pay rent.

Add on the risk of getting other tenants or their children sick, and the financial risk compounds. 

These are cabins in the woods, so we have issues like power outages, neighbor's construction noises, internet outages (a big deal when people are planning to "work from home" at the cabin), guest thought they reserved two nights when it was only one, cleaner forgets to show up... all sorts of things that add up.It seems like the littlest issue gets compounded into much larger issues that cost us lots of money.

Trying to time the market is only delaying the compound interest that can be taking place by getting started!