I would assume you'd want to cut mostly base malt. Having a higher percentage of crystals, etc. would keep the flavor and body up, as would a higher than average mash temp. I made a Saison that started at 1.038, but I think I mashed at 156 or maybe 158 since 3711 attenuates like a monster, and I even used some special B. It had a decent maltiness to it, but finished low and 4%+ abv. I would think lower attenuating yeast might be good as well to keep the FG up while scaling down the OG.