Dan, that might be possible with a Pythonscript, but I’m not aware of it, nor did I found one. Perhaps you have more luck:
https://developers.maxon.net/docs/Cinema4DPythonSDK/html/index.html
To get an Object activated use the command 1028155, please have a look at this screen capture or just check out the file. Also: ID 1029818 “Show in Attribute Manager”. BTW, the ID can stay, However, I like to delete the two letters.
Scene file / Clip
https://www.amazon.com/clouddrive/share/XQ5M4IRoXntYIzlouQU63FoLqAn8delPHbNCNbfVQBW
Please note that you can drag nearly any parameter as HUD into the interface, it will (by default) show up only while the object is active.
If you work for a long time with only User Data, you might select in one object the User Data Tab (or selveral tabs) then use the Lock Mode:
Lock Mode
Activating this option (or clicking on the icon with the two circles at the top right of the Manager) will ensure that only the modes / parameters currently open will continue to be displayed, regardless of which tools are subsequently selected.
https://help.maxon.net/us/#5824
All the best
Edited