Hi GoBuccos.
It looks like you did quite a bit of legwork already!
Itās great that you zoomed in on the type of mattress and the feel your wife likes. You are going in the right direction with your mattress selection on a few counts. As your wife is in the higher weight range with a BMI of 31 kg/m[sup]2.[/sup] sheād need more durable materials especially in the comfort and transition layers than a normal BMI range individual would need.
1 ~ Latex is the most durable of all types of foams but the layer softness and thickness are important factors as well. Post #3 here~ has more information and suggestions about heavier weights and the topic aboutmattresses for a heavier person are worth reading.
2 ~ The zippered cover is also a good choice since heavier people or people with heavier āareasā or who are more āactiveā on a mattress will wear out materials faster than lighter, more evenly proportioned, or less active people so higher density foams than just the āminimumā guidelines can be more important. A zippered cover will allow changing the top comfort layer should it start to break down or should your wife desire to exchange the comfort choice.
3 ~ The āweakest linkā in a mattress in terms of durability is normally in the upper layers (the top 3" - 6" of the mattress) that are compressed more deeply when under the weight of the sleeper and not generally in the deeper support layers so the firmer bottom layers of a mattress will have more effect on feel and performance than they will on durability for most people.
Higher BMI will wear out faster than a latex comfort layer in lower ILD (soft or X-soft choices) because there is a linear dependency between latex ILD/softness and its density. For example. 100% NR latex from Talalay Global of 14 ILD (X-soft) has 2.5 lbs/ft[sup]3[/sup] density and a 19 ILD (soft) has a density of 3.0 lbs/ft[sup]3[/sup]. Both are low densities and will wear out faster for heavier sleepers than for light ones.
The āunknownsā in your mattress puzzle are the mattress thickness and the comfort choice which are interdependent. Heavier weights would benefit from a thicker mattress because it can be more adaptable and for multiple sleeping positions. It will compress from softer to firmer more gradually which means that there is more ārangeā of compression without the mattress becoming too firm for heavier weights (or parts of the body). A thicker mattress can also be part of a specific design that requires it such as some types of zoning or layering that needs more layers to accomplish the design goal of the mattress. (It can even just be a matter of preference rather than āneedā}.
There is also more about primary or ādeepā support and secondary or āsurfaceā support and their relationship to the firmness and pressure relief and the ārolesā of different layers in a mattress in post #2 here and in post #4 here that may also be helpful in clarifying the difference between āsupportā and āpressure reliefā and āfeelā that may be useful as well.
You can also see some general comments about the properties of an āidealā mattress in post #4 here.
I agree that DIY is a more adventurous process and oftentimes it is more of a trial and error undertaking. If you donāt have the time, knowledge, and inclination it is best left to manufactures /retailers that have a great deal of experience with mattress construction.
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~ As you mentioned Arizona Premium Mattress has a few very good options and Ken can customize your selection for your wife. needs and preferences.
~ Mattress Makers offers component-style beds (zippered covers) like the url= https://mattressmakers.com/product/del-mar-medium/ Del Mar mattress[/url], I suggest you give them a call to get their recommendation for a mattress that matches your wifeās needs.
~ Nest Bedding has quite a few lines with zippered covers,.but the url=https://nestbedding.uxsi.net/P0mxZz Owl Natural Latex Hybrid Mattress [/url] seems to fit the bill.
~ Also Spindle has (10") all latex modular with a zippered cover that you may want to consider.[/indent]
These are just a few options I came across, but you may want to peruse some more of our Trusted members for other choices.
Phoenix