Wow, the ron paul jager part is awesome. lol I can definitely imagine people giving you the oddest looks. Mine isnt as apparent but I've caught at least one driver giving it a second look as they were driving past me.
I think that if I decide to make an air dam in the future that goes more forward than my current one, im going to have to make it a bit shorter because it will be even easier for it to bottom out since it would jut out more than my current dam. It definitely seems to be that the 4" is the minimum to clear most areas but even then, it can still drag at higher speeds when traveling on uneven surfaces.
What material are you using for the air dam in the finished product? And are you just using screws on the bumper? Any nuts, washers, etc?