Ice at island is prob 2-3 ft thick right now. The ice should be fine everywhere up there. If you want to snowshoe in somewhere, leon lake is full of fat 12-14" brookies and I've caught em up to 20" in there. Biggest brookies on the mesa save for an unmapped lake I know.
I really don't want to share the unmapped lake, but it is the only place I've fished with better brookies than leon, and they don't average as fat or as long usually, there are just some bigger in there. I haven't caught em but I've hooked em and seen em. I've actually caught some 3 pound monsters out of leon.