I am using 3" treated phillips scews from Lowe's. With regards to holes , I understand that wood filler will eventually pop out. What if I use paintable GE Silicone Caulk, which stays flexible?
TIA
Pet41

Why are the screw holes such a problem for you?

Silicone will fill the voids and in time could either come out on their own,cause discoloration you might not desire,retain water in the spots you fill,just where the silicone contacts the wood.It is not stainable,won't take waterproofing.

OK,back to you,

KBC

We covered this a fgew days ago. Did you look into the system I described that has no screws showing anywhere, that would be your best bet. Your silicone dots will stand out far more than the screw holes.