MD is a great idea to promote during this transition.
I’ve found you also need a company system that is independent of system management tools - some places use a help desk ticketing system, some use a change management system.
Some friends in the SMB space use a single system for their company (IT consulting firms) to track their clients, client hardware purchase dates, contracts, warranty, every change they make, Admin accounts, device ID’s, their billable time, etc.
This way all info on a client is maintained in a single place in case (this is the important bit) you get hit by a bus.
That’s a common refrain - “what happens if bob gets hit by a bus?”. Can’t have any knowledge dependent upon a single person, everything needs to be maintained in a single, accessible form, hosted on company servers and backed up.
Being a small operation, this could be a hard sell. Maybe an open-source help desk solution that you can host internally would be acceptible. The hardest part with that is defining roles and who has access to what.
Something you may consider - small orgs have difficulty documenting their systems (basically it’s a lack of manpower, you got shit to do, and documentation seems unimportant). Since there’s a transition, it would be incredibly useful to introduce requirements gathering and documentation. A typical model defines Business Requirements, which are mapped to System Requirements, which are then mapped to Technical Requirements (e.g. One Business Requirement will often map to several System Requirements, which usually map to multiple Technical Requirements).
Look into Business Systems Analysis, there’s some intro docs out there for how to do this, it’s pretty straightforward, and you don’t have to do all the detail, just having some documentation is better than none.