Triclad
 

There is a product that is used in the marine industry that allows welding aluminium to steel without intermetallic reaction or corrosion due electrolysis.

Maybe it could be used to attach Bristol body work. ?

p.s. I have plenty if anyone wants to have a play with some. You could spot weld the steel to steel and aluminium to body panel or tap and screw. A continuous weld like is used to attach the steel hull of a boat to the aluminium superstructure would probably cause too much heat build up as with a boat or helicopter deck the aluminium is 6.0 to 8.0mm thick.