[gumby79]

This is what I mean by roll scrub

Of corce the sight wants the picture sideways, ough.
I don't think it will add much if any strain on the system. Only side effect I can see is the single fixed Tire having a tendency to try and turn. similar to how you steer a motorcycle by leaning ( even drag bikes with 12" wide back tire that is square as a car tire still leans to induce the effect I'm speaking of, for turning).
Any ill effects would be most noticeable while high G-Force turning or severe side wind that causes body roll.
The greater the distance from the Roll center of the car and the U-joint Mount point the greater this effect will be. The Pivot Point must be at a central location as per the body shape and proportions through design you may be able to cheat this location towards the Roll center to minimize any ill effects. This is along the lines of what I was thinking as far as being able to do a one wheeled trailer behind a motorcycle/ bicycle.