You need to change to an electronic key pad.

I completed my journeyman certification in the Navy in electrical and electronics.

I can literally go months without any interaction other than statements and electronic deposits. 

I only have one tenant that wants to pay electronically.

It is used every electronic device we purchase.

Nothing worse than trying to keep up with a key on the beach as I specifically look for units that have electronic locks and also feel it is safer.  

Received electronic payment of rent for Property Y and recorded same into QuickBooks.

And, while you're doing so, tighten up your qualifying standards, require a security deposit and renter's insurance with landlord as additional insured, make payments due by electronic remittance only - get it set-up right from the start.The quality of the tenant is the quality of your return. 

Hi Bigger Pockets community, I'm wondering if anyone has suggestions for free or low cost electronic signature processing platforms that I can use.

That happened to us before, and was successfully managed.We aren't too concerned with managing the administrative part of the business remotely, as we use software for this (Buildium), and are already fully digital as much as we can be with e-leasing, maintenance requests online, emails, all electronic payments from residents, etc.