Hi tbizzle,
Congratulations on your new mattress
I don’t keep a record of the height of various foundations or know them off the top of my head but any 4" low profile foundation that meets the criteria in post #1 here would make a suitable choice. A google search on “4" low profile foundation” will bring up a number of options that would probably be suitable as long as they meet the criteria in the reference post I linked (slats that aren’t too far apart and a solid non flexing support surface).
Phoenix