It would take a pretty stout pull to spring the bacchetta rear fork 5mm. Doubt it would do any damage but the tubing diameter is a whole lot more than DF. You would probably have to use expander type car jack. Bacchetta has a forum on their website www.bacchettabikes.com and
www.bentrideronline.com also has a forum where such ? can be posted with liklihood of an authoritative answer. It might help to get and accurate measurement of the inside fork spacing also, shouldn't be hard to do. "Steel is real" would apply here. I know that springing my CP Ti frame takes both hands, and springing my PX10 steel frame takes two hands and a foot, both forces much less than needed to cold set the frames.
Steve