Glockfan, excellent work! your setup looks great. I don't think you will need any more filtration or water separation, but if you really feel the need to filter the vent on the tank you could try adapting a disposable dessicant filter they sell for paint spray guns. They come with 1/4" NPT M/F threads and are about 3" long and 1 1/4" round. They start out blue and turn pink once the dessicant is wet. Look on ebay or
www.Eastwood.com , search for mini dessicant dryer.
http://www.eastwood.com/mini-desiccant-dryer-2-pack.html
They are about $20 for a 2 pack. Just be sure to mount it in a protected location where it won't be getting wet. Like I said, I really think your setup is already well beyond sufficient, but its your call.
I did have one question for you and maybe I missed the reasoning in the post, but I see you have a ground rod driven near the generator. Is your service entrance grounded to this same rod or have you created a 2nd ground point? I've always understood that the generator should be treated like a sub panel where as the neutral and grounds are un-bonded at the generator and you run all 4 wires ( 2 hot, neutral and ground ) to your main panel, in order to maintain a single ground path. What did I miss here??
Thanks... Ray