I'm guessing the side car must have a driven wheel otherwise the physics of the placement of the tow ball doesn't seem right.
Yes, it would seem that the position of the tow hitch would tend to pull the motorcycle to the left. But as mentioned by Russ, this is common practice. I suspect that this is due to a requirement of road licensing and vehicle registration authorities for a towed vehicle to be centred behind the tow vehicle.
If this resulted in a tendency for the motorcycle to pull to the left, I suppose this could be counteracted by adjusting the linkages between the the motorcycle and side car. Setting-up an outfit for road use is a real art and requiries specialist expert skill and experience (or just plain luck), setting it up to also cater for a trailer would require an even higher level of skill and experience.
I have a many mates with sidecars, it is common knowledge amongst that fraternity that for many years there were only a handful of sidecar specialist in Australia, one in QLD, two in VIC and one in SA. With one of the VIC specialist dying a coupla years back, we may be down to only three.
WAG may be able to provide some more informed input.
Good point there Langers. There does appear to be some sort of differential/ final drive under the sidecar, but nothing leading from the ST. Would be keen to know how the drive was taken from the ST if in fact it is a driven wheel.
I suppose anything engineering feat is possible, but the effort, cost and practicability of such a modification would make it highly unlikely.
