A switch fuse isolator allows you to extend the tails, why not have that at height and put the cu somewhere a bit more sensible.
Messing around at height, in the dark post an rcd trip isn't the safest option. You might consider a inset cu if the wall depth allows.
Messing around at height, in the dark post an rcd trip isn't the safest option. You might consider a inset cu if the wall depth allows.