Steve,

Here is a simple thought

I have seen hydraulic cylinder assists on sweet and appleton racks for racing. They have a small servo unit that you could place in-line with your existing steering and mount a simple hydraulic cylinder to the tie bar.

other than that, yes, you will have a bit of bump steer the way you described, however I do not know how much more without the geometry to calculate it.

Scott

The problems we face today can not be addressed at the same level of intelligence we were at when we created them - Albert Einstein Or with the same level of $ - Me