As you have discovered placement is critical.  We place ours in western ND and rarely have trouble with moisture in the bag, especially if we empty them before spring thaw.  Since you probably don't want to trade farms with me to fix your moisture problem, another option that might cost a few extra $ would be to get a bagger with a truck unloader and place all your bags in a central location on higher ground that is bladed with a grade for good drainage, or better yet higher ground with 6" or more of gravel.  I'm not familiar with Madison County, but if it is flat and you can't place the bags on a ridge or higher ground, then bagging beans may not be a good option.  My experience with corn is the same as yours (we were historically wet in 2011), as the wet stuff on the bottom blends with the dry and is usually fine if you don't leave it there too long.