I’ve got 3/4” MDF over 1-1/2” t&g car decking, over 6x8” joists on 48” centers. All solid, good shape. Specs for cement board and ditra seems to suggest I should give up hope of successful tiling because of wide joist spacing. But I want to believe. And think the thickness of Mdf+ car decking should provide enough stiffness to support tile without catastrophe. Any experience, advice, death warnings before I get to work? Any special considerations for cement board v ditra for this unusual floor system? Thanks!!