I was assuming you would have VHB tape on hand for other jobs. If you don't have VHB, just use a double-sided tape from Home Depot.
Or don't use any tape - it's more of a redundancy to be on the safe side. If you use the 1-minute epoxy, the
sign isn't going anywhere. Throw in a few dabs of silicone and you're good.
Quick Set takes a day to cure...there's no reason to use that in place of the 1-minute epoxy.