What is the alternative?
I don't have a new design for you, but I'd love to read white papers from Heritage, Cato, et al on the question. It's just that the question doesn't even get asked.
Off the top of my head, subdivide the nation into 6 or 7 districts that have reasonably similar cultures--Northeast, Southeast, Southwest, Mountain, Plains, Midwest, West Coast. Randomly select a state from each region each term to appoint a judge. Let those 7 judges decide constitutional questions for that term. Reappoint judges each term, with required rotation in office.
That would be your supreme court, and only that court would have jurisdiction over constitutional questions.
I've asked him the same for years.