Hi Jill71rdh.
Welcome to our Mattress Forum! 
I moved your post a topic that fits better your inquiry.
I am sorry to hear about your RLS syndrome as this makes it so much more difficult to fall asleep or to return to sleep after waking up. Certainty making sure that you have a good sleeping environment is a good starting point to deal with this condition.
As motion isolation is of concern due to your RLS preexisting condition, both materials you are considering latex and pocket coils are suitable for motion separation (see post #18 here). Having said that … all the layers and components in a mattress will have some effect on the feel and performance of all the other layers and the mattress “as a whole” so the best way to test for motion isolation is your own careful testing on a mattress using the testing guidelines in the tutorial post (with both of you on the mattress) because a mattress that may be “motion isolating enough” for one couple may not be as suitable for another couple that is more sensitive. A foundation under your mattress would certainly contribute to having better motion isolation, but it would depend on the type and force of the movement and on the thickness of your mattress as well. Overall most manufacturers would agree that latex is “good” with motion isolation, especially the slower heavier types of movement such as turning over or bouncing or getting out of bed and are an improvement over other materials (except memory foam) but again this depends on the type of movement or vibration and the specific construction of the mattress, the ticking and quilting materials, and the materials or components above and below the latex and even the bedding above the latex as well.
You may be aware that regardless of core strength you may have a prone sleeping position is the weakest posture to sleep in for your lumbar region. There’s a bit more information about common sleeping positions and appropriate sleep surfaces here I don’t know when or how often in your sleep cycle you would switch to a side sleeping position but generally speaking as your primary sleeping position seems to be prone you would need a surface that is firmer and less “forgiving”.
Depending on the person’s BMI and weight distribution between different areas of the body a coil unit will have different comfort/ support response curves for each individual sleeper with most units being engineered for a wide range of needs and preferences and all three systems you are considering would have both the motion isolation and the edge support that you desire.
The Luma Hybrid Latex Slumber is a high-quality hybrid mattress using NR Talalay latex in the comfort layer. Luma’s perimeter edge in the CombiZone pocket coil unit (by Leggett & Platt) has smaller diameter coils around the edge offering more support and considerably reducing the roll-off and creating a more consistent sleep surface. The central third zone of the system is also providing more support in the center third zone of the unit for the hips and lumbar area. The mattress comes in 3 firmness choices and it can be purchased with or without topper (in 14" or 10.5" configuration). I am glad you also reached out to Arizona Premium as their Ultimate Hybrid Pocket Coil Latex is another hybrid mattress that would fit your criteria that uses the same Quantum Edge Combi-Zone innerspring unit as Luma does. The Quadra-Flex is also a good quality value choice that fits your criteria, using a similar tri-zoned pocketed spring innerspring (Tx Pocket Spring) with lower wire gauge around the perimeter for better edge support and 3" of NR Talalay on top and is also available in three different levels of plushness. All these choices are good for motion isolation, temperature regulation, and edge support.
You are correct in that a bad mattress can certainly exacerbate any preexisting conditions while a suitable mattress can offer some “neutrality” where healing can occur.
You are certainly looking at 3 great quality/value choices and I’d be interested to learn of your eventual decision.
Phoenix