I think an intiial x is clear, since we are getting rich if partner can sit. Over 3♠, I guess I am out of ways to show the minors, so I will unhappily bid 4♦. Over 3NT, I will just pass. Over 4♠, I think I will just bid 6♠. This might not make, but I am never really going to seven, and I don't see any way to stop short of slam.