A state commission in Arizona yesterday backed a change to the state’s constitution that would let the state set aside some of its trust land for conservation instead of selling it for development. Still, the Growing Smarter Commission dodged the tough questions of how much land to set aside and who should choose it. And although the commission agreed on a package of proposed growth management tools, Sandy Bahr of the Sierra Club said the measures would not go nearly far enough to curb the rampant sprawl in the state. The commission will now try to get its package through the conservative state legislature. Enviros are pushing their own plan to combat sprawl, which will come before voters next year as a ballot initiative.