Fitting of a problem stair hand rail

[paddypower]

Advice needed again !!
I need to fit a round wooden hand rail parallel to the pitch of the stairs. There is only one suitable wall to attach it BUT the wall is 38mm insulated plasterboard screwed to 1.5” battens at 162 centers and plastered and decorated. The wall brackets have a round base with 3 fixing holes for 1” No6 screws. Because the handrail is at a pitch, 2 of the 3 holes will line up, so if I’m lucky I could get 2 screws into one batten.
Q1. Will a stud finder find my battens through the insulation.
Q2. Obviously I’ll need to use longer screws to anchor to the battens but what should I do about the third hole that misses the batten. I was thinking of using a plaster board plug but will the insulation allow it to expand.
Q3. Instructions advice max 1 metre for fixings but due to my circumstances should I go for the 16” centers of the battens or every other one.

Any other suggestions?

regards

 

[big-all]

i would use 4x1" planed the same length as the handrail secure this to the studs then the handrail brackets to this

this will allow you to put the handrail brackets in the correct place

i personaly would angle the ends of 4x1" to look like half a hexicon 60 deg equil segments and a chamfer on all face edges

i would also screw beyond the battons[into solid wall ] as your likly to pull the battons off

 

[paddypower]

Dohh the obvious answer, thanks Big-all