Hi cold_in_the_midwest,
SleepEZ is certainly a very high quality and value manufacturer and you are working with one of the best in the country 
I know that to many people “organic” is a strong preference and well worth paying a premium for but just so you are aware, there may not be much difference between the organic Dunlop and the 100% natural Dunlop latex (outside of the certification itself) and the 100% natural Talalay is not organic … but it does use all natural latex in its manufacturing with no synthetic SBR latex. Post #6 here has more information about the different types of latex including organic Dunlop.
It’s also good to see that you are paying close attention to the spacing of the slats in your foundation or bedframe. While a larger 4" gap may not seem to make a lot of noticeable difference in the short term … I believe it will make a difference in durability in the long term and it’s a very wise precaution to take IMO.
One other possibility that is available if you really want to use the wooden bedframe would be to use a 2" slatted bunkie board (see here) or something like the rubberized coir bed rug here to even out the support under the mattress and maintain ventilation as well.
Congratulations on your new mattress :). I hope you have the chance to share what layering you ended up with and let us know your feedback when you’ve had the chance to sleep on it.
Phoenix