If you want ranchero advice ask Dave he has one wwild contrapsion on the horizon. As far as using filler, there are quite a few really good brands. I use icing (polyester filler) to go over all of my filler to fill the pin holes and to allow for finish sanding with finer sand paper and retaining a straighter surface. Use 2K primer surfacer ( this will raise many opinions on which is best) block sand and seal with epoxy primer. Now your project can sit until you are ready to paint.