If you can’t use your body weight effectively as movable ballast, you need to modify your driving as well as add a little weight to the sidecar. This is an instance where adding fixed ballast is a good idea. You may want to add a some ballast to the chassis of your sidecar. Out near the sidecar axle, inside the triangle formed by the contact patches of the three wheels is where you want to put it.

You are fortunate to have a fairly stable combination, at least by all reports(I haven’t personal experience driving that combo).

Since you probably can’t shift your weight much into the corners,you are going to need to slow down. Get your speed way down BEFORE you get into the corner and use a little throttle coming out, controlling your speed with the front brake and throttle.

Practice in a safe, flat, open parking lot. Mark out a tight corner with an 8′ lane and practice slowing for the corner and using the throttle and front brake to get through it.

Modifying your front end for less steering effort will also help you in the corners. It is expensive, but it can be worth the money, especially if you have limited upper body strength or range of motion. Contact a profesional sidecar builder or shop for help with this.