Are you really sure it is absolutely impossible to remove the ring without holes?
Personally I haven't yet found it necessary.
In extremis I have in the past resorted to heating the whole lens in an oven (a cool oven, obviously... gentle heat!) and then using freezing spray or ice to cool the ring (I cover the glass with a rubber disk and a cloth to protect it).
For grip a rubber bung of just the right size usually helps. (Laboratory suppliers on eBay!) Most bungs are quite hard rubber - which often works, but can slip. for better grip a circle of softer latex over the bung gives more grip. (I bought some latex 'exercise bands'. They are just latex ribbons). In a few cases I have resorted to hot gluing something to the rim, too.
Vibration also helps. Sometimes trying to tighten it first, before removing, works as well.
The only total failure I've had is with a 1930s Aldis lens where an aluminium ring had cold welded into an aluminium casting. I read somewhere (maybe here on APUG?) that aluminium can't actually cold weld under these conditions, it is a myth. Myth or not - it was totally ***** stuck! In my desperation I actually splintered the ring - although about 2/3rds of it remained 'welded' in place, leaving me with a scrap, unrepairable lens.