"I also was told that bonding
the copper to the iron with a wire when connected with isolating
junctions
does not cause corrosion. Opinions? "

I don't see how that's possible. The classic experiment showing
galvanic action is to take two different metals, place them in an
electolyte, and measure the voltage between them. When connected by a
wire, the less noble metal will corrode. This is them method used to
protect boats. All the underwater metal is bonded together and zinc is
used as the sacrificial anode. At best, I would think using a bonding
wire across the dielectric unions would move the point of corrosion and
perhaps distribute it over a different area.