Squaring off a rail!

Morning.

I have a hollow wood board I made some years ago before I realised what rail shape I would want later on.

They ended up very soft towards the rear - probably 60/40 at a guess - but I want to make them harder!

I’m thinking of just building up some layers of fiberglass along the edge so I can shape a harder edge.

Any other thoughts?

Maybe build it up with cork first as a filler then glass over?

I was thinking to avoid cutting the rail off and replacing but it’s a possibility.