Hi @johnnyfitz - Thanks for reaching out! Like @PatrickB said, the Katoola microspikes tend to do a great job not stretching out when worn over boots in their size range. Your XL pair should hold their shape well when used with size 12 Chilkats.
Are there any neat winter activities you have planned that have you looking into microspikes? We'd love to hear how you're getting outside this year!
Thanks again for bringing this question to the community. Hopefully this helps!