Another design is apparently used on some european city bikes to keep the front fork from rotating to the side. I have seen it mentioned in the utility bikes area as I recall. This is a setup with two springs running from a bracket on the fork steerer tube bottom to a bracket mounted on the down tube. Still allows normal steering but the springs are apparently strong enough to keep the fork from rotating much when the bike is on the sidestand or center stand.
A email to a Dutch dealer might turn it up as an add on device. I may try making something similar for my utility bike.