3. Trade Dylan Carlson and Tyler O'Neill, move Paul DeJong to 2B
While this doesn't favor the fielding as much as it does the offense, this could be another option for the Cardinals to help with the logjam of the middle infield. This would leave Edman to play SS for the rest of the season and move DeJong to 2B to keep his hot bat in the lineup while keeping Gorman in the DH position.
Donovan has shown promise in the outfield by making game-saving catches in left field, and trading Carlson along with O'Neill would be a good starting point for a trade package for starting pitching. This also leaves room for the #1 Cardinals prospect and #1 MLB.com prospect in all of baseball, Jordan Walker, to come up and fill the OF role.
The only problem that comes with this move is the massive downgrade that occurs in the fielding department. With Carlson and O'Neill being marginally better in the OF than Walker, it would result in a downgrade in the defensive department for the Cardinals.