What Next for Problem Pergola?

Our South-facing pergola was originally stained with a white Cabot oil based solid stain then re-stained years later.  Eventually the stain started flaking off and we had a bad mildew problem.  We have now sanded, treated with Concrobium to kill mold (which is already beginning to return), and will be using a mold stain remover (hydrogen peroxide, ph adjustor, etc).  There are still some vestiges of white in knotholes and crevices that have resisted sanding and stripping efforts but we don't really mind them and would probably like to keep the pergola close to the color it is now - a light wood tone.  Our main priority is not to create a maintenance nightmare - we can tolerate something fading gently but need to get some years out of this job.  Is there a semi-transparent or other product that fills the bill and would help to prevent mildew? We already tested a dark, semi-solid, and that looks bad over the white.  Also, after all these steps, do we need to still use a deck cleaner and brightener or can we move right into staining?  TIA.