Tried that lock-ring tool... Don't bother with it.
The teeth aren't very deep so they'll jump out because of how wide the engagement is and just strip the holes.
Here's the solution you need... String
Or light rope ... I happen to have a lot of kite line lying around.
Tie a bent bar or spanner...
Crikey
>£45 for delivery
Ouch
Going for this option instead
https://www.performancelinebearings.com/product/bosch-gen-2-lockring-tool-sprocket-nut-tool-by-icetoolz/