Yes, the sheeting of the bottom will create the "D" that gives the wing it's structural integrity. If you don't use the 1" piece to support the trailing edge you could build a twist into the wing that will be permently locked in. Some plans call for washout (not the SE) where you raise the outer trailing edge and then lock it in when sheeting. If you have a table saw you can cut out the 1" from scrap 2x4.