Of all of the MOA rallies that I've attended, the Minnesota State Fairgrounds has almost as many trees as all of them combined. Shade shouldn't be a problem for most. If the fairgrounds open up a few buildings to campers (as many of them do), most of us will be able to camp in the shade.
Being a native, as the event draws near I am going to start a thread for out-of-towners to ask questions pertaining to local culture, food and beer. The Twin Cities is home to many microbreweries and many, many great restaurants. Como Park Zoo is close by and the AA series St. Paul Saints baseball team is within easy walking distance of the fairgrounds. Lots to do here, folks.