Eliminator width

Forgive me if this has been discussed. I have been searching and haven't found information on this topic. I have noticed the width of most eliminators is smaller than most cars. I am gearing up to build one and was wondering if y'all have any advise on this class, specifically the width.
 
Mine is just under a 1.5inch wide. Going that thin on a elim. you will have to make some spacers for the wheels but less surface area should mean less air to move. At 7-11mph may not make much of a diff. but you never know.