The month of May on any given lake in Iowa can be great for walleyes! My go to jig would be 1/16th ounce jig head (pink or orange) tipped with a minnow. You should be able to get leeches by then and it's hard to beat leech and a bobber as well. Not really familiar with McBride but I've got some buddies who do really well there for walleyes most of the summer!