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If the fence is not on your property, you cannot complain about anything they do with it (including painting) unless it is against some city or county ordinance.
Also, you don't have the right to hang any plaques on the fence - it's not your property. They could charge you with trespassing for this.
While the owner of the property certainly has the right to be involved, the tenant also has rights that must be respected, after all, the tenant is paying to live there and is entitled to quiet enjoyment of the premises. The tenant likely has standing to be involved just as the owner does. You certainly have the right to your opinion, but I don't think it is legally fool-proof.
Trespassing is a criminal and civil matter - you could be charged with both.