I think it is a great idea. The playfield glass would be great for those wanting a viewing before you go into the grave.
Wouldn't it be good to see a cemetery with an Anglican section, Catholic section, Jewish section, then a Pinballist Section, with the backboxes (or granite reproductions of same) all lined up....
I don't think I could bear a cremation - to see a good cabinet go up in smoke would make the whole occasion even sadder.