Wood Filler Recommendation Before Installing Glass Clamps

[RainbowWrighty]

Hi

Currently prepping the stairs to install glass balustrades. The previous plywood panels were installed into the groove as shown in the pics. The groove is about 10mm deep and 7mm wide.

I plan to fill that with a drillable wood filler and then install clamps for glass balustrades.

What wood filler would you recommend for this?

Thanks,

RW

 

[Wayners]

Fill with wooden strips not an option?

 

[RainbowWrighty]

Fill with wooden strips not an option?

Could do, hadn't thought of that.