Hi MVincent,
There is no way to know this for sure without a reference point of a mattress that you have tried that has known layering and that can act as a model to “approximate” but I can tell you (and I’m sure you already know) that your circumstances and body type is somewhat challenging.
As an athlete that is “outside the averages” of most other people … a mattress can be as difficult to “fit” for you as a suit where your shoulder width and upper torso relative to your waist and hips is out of proportion to “normal” sizing.
One of the keys to “mattress success” is how far each area sinks in relative to the others which is not just dependent on the weight of certain parts of your body but the surface area of that part that comes into contact with the mattress as well (force per unit of surface area). Higher weights spread out over a larger surface area will sink in less while the same weight spread out over a smaller surface area will sink in more. Because the body is not a flat surface and it’s contours and surface area changes as you sink in deeper and because of the many variations in sleeping positions which present different body surface areas and weight concentrations to the mattress … this is very difficult to predict for any individual. Preferences also play a role here because some people prefer a firmer or softer surface feel than others.
Side sleepers generally need a thicker comfort layer and The Ultimate Dreams Latex Ultra Plush (I’m assuming this is the mattress you are considering) is certainly “in the range” with 1.5" of softer quilting and 3" of latex (with your choice of firmness with a goal to “allow” your shoulders to sink in enough) for a total of 4.5" that will accommodate your shoulders in the side sleeping profile. The key would be to choose a softness level that will allow your shoulders to sink in as far as they need to until your torso comes into contact with the mattress. Once your shoulders have sunk into the mattress enough, your upper torso will reach the mattress and the surface area starts to increase significantly which means that the amount of further sinking in with the upper body will slow down. If your shoulders are “allowed” to sink in enough … you may be able to get away with less pillows.
The challenge though is that the same softness and thickness that allows your shoulders to sink in enough may also allow your heavier hips/thighs to sink in even more but because they also have a greater surface area than your shoulders (on your side) the weight is probably distributed over a larger surface area than your more pointy shoulders. The key is to have a comfort layer that is just thick and soft enough to allow your shoulders to sink in as far as they need to (and you can choose this in consultation with Chuck) while having a firm enough support layer that will “stop” the heavier pelvis from sinking in further than it should once it “goes through” the comfort layer (and if the comfort layer is soft enough for your shoulders it will generally allow your hips to sink in even more easily until they reach the support layer). In other words you will likely need a firm enough support layer and I would ask Chuck about this specifically (the support layer firmness) because you would probably do well with a “firmer than average” support layer regardless of the comfort layer you choose. Of course if you are looking at their all latex mattress then you can choose the firmness of the support layer as well.
Your circumstances may also warrant some center zoning where the firmness under your hips/thighs is firmer than the rest of the support layer because this will “stop” the hips sooner and still allow for the use of softer materials under your shoulders to allow them to sink in more so you would be sinking into the mattress more evenly.
Quite frankly, I would be tempted to do some local testing on latex to get a more clear sense of what layering combination would work best for you. There are some very good quality/value possibilities in the Los Angeles area in post #2 here and with your more challenging circumstances (a more difficult than normal balance of “allowing” your shoulders and “stopping” your hips so that you are sinking in evenly), I would suggest that some personal testing on local mattresses could be very worthwhile. You may find a mattress that is perfect and has good quality and value which would avoid the risk of an online purchase or in the worst case you would gain some valuable experience that you could use as a reference point for an online purchase.
Phoenix