would this work also with a cotton knit fabric for the back and regular cotton on the top I did one with the cotton knit on top but it wasn't very easy I am doing this on a longarm I know I would have to be careful not to stretch the knit fabric but wondering has anyone tried this and if so did it work??

I am glad to hear you can do this. I will look for design backs in my stash.

I have followed the pattern on my backing for quilting design and it worked great!