LEGO Derby Car Dimensions

My daughter entered a Girl Scouts LEGO Car Derby. There were specific rules as to the size of the car so I wanted a quick way to determine if the car was "legal".

The dimensions for the contest were different than for a regular Pine Car derby but they are close. The main dimensions I've seen are the minimum clearance (3/8") and the weight (5 oz).

I made the first version but during the contest I notice that a lot of the contestants violated the rule about a 1/2" flat front nose but using