Thanks so much for the quick response. I was confused about the ILD of the 6" base myself but Ken at Arizona Premium was the one that mentioned the 46-50.
Also thanks for the pointer on the cover–based on research, it seemed like this cover might be my best bet.
My only other thought is to keep the same base but go with two 3" (rather than 2") layers from Arizona Premium, but the top layer would be 19 ILD rather than 21 ILD (which would be followed by 3" of 28 ILD). Their 3" blended toppers only come in the 19 and 28 ILD options, as you probably know. What would your thoughts be on this configuration?