While a 3 wheel car isn't going to be as fast as a 4 wheel car in a steady state corner, because your car only lifts the inside tire center off I'm almost inclined to let it slide. You could try a stiffer rear bar, but it might hurt your lap times.

You certainly won't be alone. I have seen pictures of the 11 car testing at VIR with the inside front almost a foot off the ground, but I can't find any right now, so this will have to do.