Yes it helped but doesn't stop the bugs in the crevice, but that's only because I have a short cabover (bed goes from side to side, that is head to toe goes side-to-side). The extended cabover which is 12-18" longer will still catch the air and direct it under the cabover.
What did better than the bug deflector was a simple vinyl trim J-channel (one that goes around house windows) attached to the bottom of the cabover to reduce the gap which reduce the airfllow. This completely eliminated the bugs in the crevice.
P.S. Sorry about the E/W/N/S abbreviations as I don't use TC lingo because I realize not everyone is familiar with the terms but thought those would be okay because they are so widely used.