I do not think you will gain much of anything by removing the cats, except for nasty exhaust odor. You may find that a "reputable exhaust shop" will refuse to work on your car, as they are subject to extensive legal problems if caught bypassing the catalysts. You do not need to remove the cats to replace the power steering hoses. On my 83 V12, I removed the steering rack to subframe bolts and that gave me enough room to remove and connect the hoses at the rack end. I would disconnect them from the pump and steering cooler first, then reconnect at the pump and cooler last, so you have the hoses free at the rack end for easiest installation.

 

Cats catching fire is very rare though, and a car has to be quite neglected to get to that point. The V12 is a massive lump and I really noticed no difference in underhood heat between having cats and not - it's still a big engine in a small space. That being said, with the fan and fan clutch in good order, there is a lot of airflow through the engine bay.