I have a 10metre (30ft-extended)wooden ladder, a 21ft fibreglass/aluminium extension ladder and a 7ft fibreglass step/extension ladder on my Faults truck.
Both of the extension ladders have out of factory white paint on them at the top so that you can see where the top is when setting them against a pole in poor light.
The base used in Oil-based paints will attack fibreglass and I would recommend that if any painting was to be done, use water based paint.
George,
LONG ago, we used to coat our wooden ladders with linseed oil
Mate, That was one of the first lessons I learned as an Apprentice Line Mechanic.
"Here's your tools for today son, a paint brush and a can of linseed oil and 28 extension ladders".
Oh well, at least I got paid for it.