Hi MikeM,
The Electropedic mattresses are IMO certainly better value than something similar from many retail outlets but are not in the same “value range” as many independent manufacturers or online purchases (including some on the Los Angeles list in post #63 here). They are however 2 sided latex mattresses which are much less common (partly because latex is very durable even in a one sided mattress) and which adds to their value compared to one sided mattresses.
Your testing here certainly helps to “point to” the best construction for you though.
It seems that you have been somewhat happy with thinner comfort layers than is “typical” for side sleeping which leads me to the sense that you are not as sensitive to pressure issues and/or are more evenly proportioned. I would tend however to a slightly thicker comfort layer only because if a layer this thin has a soft enough support core underneath it to contribute to pressure relief needs … then it will likely be too soft for correct alignment (as in the 24 ILD support core being too soft). The 32 would certainly seem closer but in side sleeping … the thinness of the comfort layer and the transition into a firmer support core may well create pressure issues over the course of the night. The fact that the 36 felt too firm (under 1") also points to this as it is not a great deal firmer than the 32 (4 ILD is about the amount that people will feel a difference).
The fact that you were OK on 32 ILD latex also point to the fact that you are not as sensitive to pressure issues and also that you prefer a more “on the mattress” feel.
With the 2" 19 ILD over the 32 ILD at custom comfort … I doubt that you would have sunk in too much for alignment even though you may have sunk in more than your “preference”. The amount you “sink down” (alignment) is more determined by the support layer than the comfort layer. The amount you “sink in” (pressure relief) is more determined by the comfort layer. Choosing a higher ILD in the comfort layer will have a greater effect on pressure relief and overall feel (on vs in) than it will in how far you “sink down” for alignment although they are of course interconnected. As long as the pressure relieving cradle is deep enough for you however based on your sensitivity to pressure (over the course of the night) and your weight distribution and as long as the “gaps” in your sleeping profile are “filled in” (difficult to slide your hand under your waist when on your side) … then a shallower cradle is fine.
My sense though is that 2" may work better. A good value reference point for a 2 sided mattress with 2" of latex over a 5" core (9" of latex in total) and a natural cotton ticking quilted with wool (which is softer than cotton quilting because wool isn’t as dense as cotton and is more resilient) is here www.mygreenmattress.com
In terms of the ticking material (without any quilting) … the less stretchy it is and the tighter it is … the more effect it will have on the latex below it. While a good terry cover will be fine in terms of protecting the latex from oxidation, ozone, and ultraviolet light (what makes latex break down), it will not protect the mattress from spills and any stain will void a warranty. A thicker looser circular weave ticking material or a material that is more stretchy (such as that used in the Pure Latex Bliss) is probably better yet than terry in terms of having less effect on the latex. It is also usually more durable than a thinner lower quality ticking material. This adds to the price however since ticking materials can add significantly to the cost of the mattress … especially if it is finished on both sides.
This is why all mattresses should have a protective cover over them … regardless of the ticking material. The very thin covers that are both breathable and waterproof (a breathable membrane with a thinner cotton or blended material) are usually chosen when there is a desire to have the least effect on the mattress.
Other people will choose a wool mattress pad/protector as wool is water resistant (not waterproof) and is also very breathable. While it will affect the feel and performance of the latex more than a thinner protector … this is also a very popular tradeoff as long as the wool doesn’t create pressure issues with a mattress that is otherwise “on the edge” of what is needed in the comfort layers in terms of thickness and ILD. Cotton quilted mattress pads/protectors are sometimes also chosen for their breathability and feel but they are the least waterproof of all and you would have less time to remove everything over the mattress in the case of a spill before it soaked through to the mattress.
When a mattress ticking includes wool or another quilting fiber or foam … then a thinner mattress protector is usually best as having wool in the mattress quilting (or some other fiber or foam) and wool in the protector will often be too much fiber over the latex. Overall … the thinnest protector that has the level of water resistance and breathability that you want will have the least effect on the feel and properties of the mattress. I agree that wool quilting in the mattress under a wool protector is both redundant and probably “negative” in its effect … moreso even as the wool (or other quilting material) compresses over time.
While there are several zip covers/tickings available beides SLAB however none of them are quilted on two sides. Of course the layers inside can be removed and flipped but this is a pain. There are also mattress tickings that are not quilted at all which of course could be used on both sides.
Quilted …
https://www.foamorder.com/latex.php#organicpillowtop
https://www.sleepez.com/mattresscomponents.htm
http://www.supremequilting.com/home.php (In Canada. Have both a natural wool quilted cotton over and terry cover)
Some cheaper additional non quilted choices
http://www.foamforyou.com/terry_cloth_covers.htm
Hope I managed to answer most of your questions 
Phoenix