Covering old brown stain

We replaced the floor of our old deck with PTW in Sept 2012. We want to stain the deck with TWP 1500, Dark Oak after treating it with Restore-A-Deck Cleaner & Brightner. However, we replaced the railings with PVC due to the fact that the deck is above our walk-out basement and faces southwest so it gets blasted by sun in the summer and as we are in CT gets snow/ice in the winter. Trying to keep up with the wooden railings as they twisted and popped was becoming a real issue. The old posts that run to the ground and some of the joists were treated with a dark brown stain. The new railings are white. Does anyone have any advice about covering the old posts? We are thinking of going solid white after applying a stain primer but are unsure if this will work. Thanks.