In article ,
says...
I need one of these to fit my new shower-bath, but the problem is the wall
is a stooving and I will be fixing to wallboard. The ones I've seen (in
Argos and Next) have small diameter brackets which haven't a hope of holding
up the weight of a wet curtain and its own weight when fixed to boards.

So chop out a bit of board and replace it with ply?