71 Duster 360 turbo build

Installing a new fuel sending unit which led to rebuilding/rewiring my gauge cluster. While I’m in here I was thinking about adding a couple red LED’s as a high AFR warning. Anyone here good with circuits? I’d like to tap into the wideband 0-5v output to trigger a relay at 2.0 volts which would equal 12:1 fuel ratio. I don’t understand why this isn’t something that already exists on the market. Maybe I just can’t find it?