Hi Royalty.
That sounds like a fantastic course of action. Please keep us posted on your findings.
Yes, you would very likely be able to keep some of that plushness with a 1" topper as opposed to 3" without compromising your support and alignment.
To answer your question about a softer layer under a firmer layer…there is a time and place for this and Phoenix talks about it in detail here.
I hope you find some great insights there!
NikkiTMU