Fantastic to find someone else is still using these wonderful machines (as of 2016 anyhow).
My Lombard's main battery has died, and so has the PRAM battery. I did try making a new PRAM battery as the correct cells are available to buy, but it has been unsuccessful.
Must try to hunt out another old battery and leave it plugged in as you suggest.
It may be 18 years old, but the Lombard is my preferred 'laptop', both for the OS 9 software and the well designed hardware.