Help! Frozen Pin Removal.
Sounds like that should be Prat Catamarans, doesn''t it?
No experience at all, I''m afraid, but is drilling them out an option? If you could cut/grind them back to the surface of the aluminium, you might only have to drill for the depth of the aluminium wall thickness at each end of the pin.
Either the steel is removed and the centre part of the pin drops down inside, or the pin starts to rotate, whereupon you stop drilling and start pushing.