Have you had a look at the API?
You could use a PowerShell script to update the custom property and then call that from a schedule or an alert action.
Nice example of how to do it on the OrionSDK GitHub - OrionSDK/CRUD.SettingCustomProperty.ps1 at master · solarwinds/OrionSDK · GitHub
More details on getting and installing the SDK from the main page- GitHub - solarwinds/OrionSDK: SDK for the SolarWinds Orion platform, including tools, documentation, and samples in Powe…
I was thinking that the API was probably the way to go, but I was wondering if there was a clever way to calculate a custom property already in the product. I have looked and not found anything and this is probably the best answer.
Thanks for the response!