I'm not talking about extending or moving the bump stop. The shock was internaly fitted with a spacer. This reduced the shock eye to eye length slightly.
The bike now sits 1" lower. I know this through before and after measurement, and through observation that my workshop stand is now too tall to go under the sump guard. The tyre is in no danger of contacting the mudguard at any stage of extension or compression and overall suspension travel has been reduced, not extended. The full compression clearance should be unaltered, the shock is shorter at maximum extension, bringing the tyre closer to the mudguard, but the eye to eye shock length at full compression remains the same. I didn't measure this before and after. The leverage ratio of the suspension remains unaltered. No preload adjustment was needed, however as the travel has been reduced to apply the same percentage of sag means slightly less sag is required.
Had I changed the length of the dog bones, the leverage acting on the shock would change and the preload would need adjusting accordingly to get the same sag settings.
An aftermarket upgraded shock set up to the appropriate length and travel would be the way I would go to reduce the height of the bike. The suspension though basic and not brilliant is well suited to the bike IMHO, and upgrading for me will be only if the shock needs replacing anyway. That of course would highlight the performance of the forks, and to balance the quality of the suspension would mean fork upgrades too, and on a bike that handles perfectly adequately for its performance, handling and ground clearance, that would be overkill for me.