I'm now starting to get an idea of the setup. This is the chassis in position with 9" sidecar wheel lead, but a bit further away from the bike than it will end up to allow adjustments. As I thought the forward mounting on the chassis is far too far forward to be of any use so will need to make more split clamps. The body will be going off for paint at the beginning of March so no rush.
Mr Waitrose's grocery boxes are ideal for this job!

Looking good. Taking shape.
Curious onlooker: 'scuse me, what geometry you using on the sidecar?
You: Oh, the Waitrose geometry.
Curious onlooker: Ah. Right.
(Sculks off to consult Google AI) 😂