: my worry is that it will be difficult to sand over these ridges
: without sanding down to or thru the glass.

Ah ... I see. I haven't had that problem, yet! I don't see any way around this problem. You won't be able to shift the strips back into alignment because of the glass/epoxy skin. I'd either ... leave the ridges alone ... or sand 'em as best I can and maybe add another thin layer of resin if necessary.

Ken