Hi LookingNow,
Yes. Thinner layers or thinner mattresses will have less “range” of compression from soft to firm (see post #14 here) and it may maintain much of the surface softness but feel firmer overall because the layers would compress to a greater percentage of their thickness so I thought it may be worth trying as an option (after your other combinations) to see if it made any difference (although as CentralPA mentioned I would go very slowly with “incremental” changes and not make rapid changes that your body doesn’t have time to keep up with or identify a “pattern” that you can assess).
Phoenix