I started using the Redneck T-Post feeders
and that is one thing that I've noticed with it, the rain soaked feed issues aren't there. It is a small single port feeder so I can keep the back of the feeder facing to the southeast, the predominate direction moisture in the form of rain or fog comes from. Since switching from the large multiport feeders to these, moisture contaminated feed is no longer an issue.
The little feeders aren't good if you do not reside or are near where they are located as you need to fill them regularly. I check all mine twice a week.
Maybe if you closed/sealed one or two of the ports facing the predominate wind direction, the moisture issue would get better?
I was a bit worried about a single port but the deer line up real nice and take turns.