electric build

I build this rig, an electric bicycle with a sidecar, the battery  under the floor of the chair weight 50lbs, this rig will probably never go over 20 miles an hour.

As I have read would happen the steering pulls to the sidecar, when the sidecar wheel dips. Both front and rear wheels have geared motors which gives life to the pull of the handlebar.

I live on a small island and the road surface has every unevenness in the book

It seems obvious that I have to add a steering damper, any suggestions?