Hi lookin4sleep,
As far as I know their queen toppers are 60" x 80" (standard) and the covers don’t have a zipper but they have been known to make alterations to their standard sizing so it may be worth asking. You could also ask them to ship it without the cover and it would be easy to cut to size if it was a little too big (using an electric knife is the easiest).
Some of your options I’m aware of in Des Moines that would be worth calling are in post #6 here (I don’t know the individual products or toppers they carry other than what is on their website).
Phoenix