Chubby..nice helpful reply!!
Anyway, I think the answer he is looking is, In theory Yes, however this is far from ideal or truly correct.
What Chubby is hinting at is the fact that the Isolator should be located as near as practical, in compliance with other regulations, to the shower, so as to aid safe and proper Isolation when not in use, in emergencies and for the purposes of maintenance.
In an ideal world this would be in the room where the shower is to be located, however if this is not a practical solution, the wall outside the door is usually acceptable.
They do make 45A Pullcord switches however, and I would suggest that you consider this option first.