Hi skyjumper,
Hopefully you’ve read the tutorial post here which has a step by step approach that can save you a great deal of time and frustration.
It sounds to me that you have completed all or most of step 1 and step 2 and your next step is step 3 which involves identifying the better options and possibilities in your area and beginning your personal testing so you can translate what you are reading into personal experience.
Spindle mattress actually has two “basic” mattresses (one has two layers and one has 3 layers) but both of these have a range of options for many different layering combinations using different firmness levels for each layer so in effect each basic design is the basis for many different mattresses. They would certainly be well worth a visit to test a range of layering combinations for the types of Dunlop latex they use in their mattresses.
Some of the other options and possibilities in the Providence, RI area I’m aware of are listed in post #4 here.
Phoenix