Hi tlsmith,
I forgot to mention that there are a few more memory foam or gel foam online options listed in post #12 here (some of which are not members so make sure you don’t ask them for the discount because they also won’t know what you are talking about :)) but I’m not sure if any of them carry a gel foam / latex hybrid mattress.
Of course you could always build a DIY mattress if you wanted to go it alone without the help and guidance of a manufacturer that makes specific mattresses by buying all the layers separately that you believe would be close to what you want. Some of the better sources for different materials are in post #4 here if you are up for the challenge … and sometimes frustration and cost (if you guess wrong) … of going in this direction.
Phoenix