[slob]

I’d want to make sure there was 1/2” plus behind the weld on the tube coming up from the rear engine mount. Then grind off the remaining grab handle.
As others have said, probably best to remove the pillion padding/fit cowl and remove any rear pegs. Maybe fit a single race seat?
As ever, keep in mind that an insurance company could regard a tail chop as a write-off.

2-1 pipe is a great idea, sacrifice a couple of HP for a weight saving but the 900 system ins going to be a bit of an arse to fit to a 1000DS.

Check out the DesmoDue racing calendar and have a wander round the paddock for inspiration.