why I suggested a larger hole further down on that bulkhead .

You have any thin plastic rod that will bend as you push it thru the hole ?  ( make a slight bend in the end first ) then you can attach the wire and pull it thru .

Or something else that would suffice as a fish-rod ?  Like a long enough zip-tie ( with the ratchet end removed )  or something that will bend but rigid enough you can push it along .