Enclosed Car Trailer Buying Help!

We just downsized from a 40' gooseneck to nothing yet. We had a dragster so the length was needed but I rented a 20' V-nose to go pick up the dart and it had room to spare but not much. Personally I don't think the V-Nose helped mileage at all and have heard theories that the increased frontal area actually hurts mileage. We will be pulling about an hour to the track every weekend next year and I still haven't decided on going with a cheap open trailer or getting another enclosed trailer.