It does look like Caesar has to go. It seems you've got two options as to how to proceed:
1. Chop a settler after the Work boat and hope to get the copper site before the Roman. At the same time you can research AH next instead of the Wheel so you'll know where horses are by the time the settler finishes. This could provide an alternative to the copper site.
2. Build a settler after the work boat. Research IW next. IW currently shows 23 turns to research, but if you use the fishing boat on the clams and work that you should be able to get IW done about the same time the settler finishes. This would have the advantage of denying iron to Caesar if one is available in between Rome and Moscow, but if iron doesn't show up in a convenient spot you could end up losing out on the copper.
1. Chop a settler after the Work boat and hope to get the copper site before the Roman. At the same time you can research AH next instead of the Wheel so you'll know where horses are by the time the settler finishes. This could provide an alternative to the copper site.
2. Build a settler after the work boat. Research IW next. IW currently shows 23 turns to research, but if you use the fishing boat on the clams and work that you should be able to get IW done about the same time the settler finishes. This would have the advantage of denying iron to Caesar if one is available in between Rome and Moscow, but if iron doesn't show up in a convenient spot you could end up losing out on the copper.