I am hauling a 6x10 enclosed trailer with a minivan (OK, stop laughing...it's my wifes ). I am debating on getting one of those "bubbles" for the front of the trailer and was wondering if it would really make a significant difference in gas milage? The other option was a wind deflector wing that would fasten to the van itself (kind of like a spoiler affair). I've seen them years ago, but don't know if they even exist anymore. Any advise?