Have the tenant sign a Lease Amendment indicating that the tenant is responsible for the cost of installation of the charger, any maint and repairs, and also removal cost (if desired later by you or the HOA). 

We use Buildium to review applications, sign leases, etc.

In my experience, being upfront about wholesaling and explaining that you’re looking to assign the contract has resulted in numerous signed agreements.

Just be 💯 certain that you'll be able to refi that HELOC debt off when the time comes.However...At this stage in your investment career, I would URGE you not to sign up for negative cashflow in the hope that "the market" will save you.

For example, a duplex that's on the market is selling for $440,000 and the tenants are currently paying $850 per month and are signed until next July 2025.

What Drew said.Plus, insist on signed estoppel agreements before closing!

The rental values alone suggest a lower tier neighborhood but are their signs the neighborhood will turn in the near future?

Did you know that each week, several thousand people sign up for BiggerPockets, but nearly 10,000 RETURN to BiggerPockets after being away for more than 90 days (often for years). 

There are some positive signs on the horizon.

Go to Etsy and search for "rental property tracker," and you will find hundreds of nice spreadsheets to track 10-20 rentals, usually for under $10.Software has extremely helpful features like online payments, marketing syndication (click a button, and your property is advertised on multiple sites), electronic document review/signing, maintenance tracking, and owner reports.