Should I use a hyphen with a phrase involving "then"?

In this sentence: "before migrating to lower SoHo, and the then still fringe neighborhood of Chelsea," I feel like "then-still" should be hyphenated, but I can't find a rule in the Chicago Manual of Style about it. Any ideas?

Solution 1:

In a comment, I wrote:

Because you should only use hyphens when some confusion would otherwise arise, which misparsing are you attempting to avoid here? Books don't hyphenate this.

In a comment, FumbleFingers wrote:

Yeah - hyphenating just still-fringe doesn't look too bad either (but just then-still looks weird). As a matter of fact though, when I just searched Google Books for the structurally-identical sequence the then still unknown (person, thing, idea) I didn't see any hyphenated instances in the first couple of pages of 636 results returned.