Hi sfs244,
Calling Shawn is by far your best option since a more detailed conversation on the phone can cover much more ground than forum posts when it comes to more nuanced or complex information and they will have much more knowledge about the options you have available than anyone else when it comes to their mattresses.
I do have a couple of suggestions that may be helpful though before you talk with Shawn about exchanging layers.
It may be worth trying S/F/M which would create a little more softness underneath the soft comfort layer that may be “in between” this configuration and the S/M/F that you tried initially. Some people may not notice much difference between the S/F/F and the S/F/M but it would be well worth a try to see the different it would make for you.
This sounds like it is fairly close and I would also consider trying a M/S/F combination since this would be one step softer in terms of pressure relief than M/M/F. It would also be “in between” the S/M/F layering that you started with and the M/M/F.
Some of the suggestions in post #2 here may also be helpful (especially to make sure that any mattress protector or mattress pad or the foundation you are using isn’t contributing to any of the issues you are having).
Phoenix