C-15A and F-15A Vehicle Weights

[RichCam]

Hello Guys,
My question concerns the chassis weight of the C-15A Cab 13. At present, my C-15A Cab 13 is to be fitted with an aluminum radio box. I don't have a vehicle scale in my shop but the radio box can't weigh more than 600 - 800lbs. The vehicle plate indicates a chassis weight of 4960 lbs or 2255kg.

In order to avoid a "Commercial" registration, (Registered Gross Weight 4500kg/9900lbs or greater) could I indicate a Registered Gross Weight of 8500lbs or 3864kg? This is what is indicated as the maximum allowable gross weight as per the General Motors of Canada issued vehicle plate.

If I do so, would that not allow me to add roughly 2740lbs of fuel, gear, etc. to the vehicle before I come close to the 8500lb MAGW? (8500 - (4960 + 800))

Fully loaded, 8500lbs is still below 9900lbs if I had to go over an Inspection Station scale.

Simply, is the 4960lb designation accurate for the Cab 13 C-15A? Is the Cab 13 F-15A heavier because of the flathead 8 Ford engine?

Welcoming your wise comments!