Team 5720 Frame Perimeter Question

[mjv5720]

Since this years robot requirements rely so much on measurements, I was curious about the frame perimeter.

Here is a link to pictures of our robot: http://imgur.com/a/pu6jp

When measuring the frame perimeter, does it have to be an exact rectangle? By that I mean can it curve in a little bit. Right now as you can see our robot's front two wheels aren't as thick as our tank treads and so if we put a string around it it has a more trapezoidal shape to it. Does that matter? Or should we be measuring it from outside edge of the tank treads all the way down the side of the robot?