Working on cargo box for back rack of ATV

I've been out taking measurements for the size of the rack on the back of my ATV, since I can't find the ones I made last year, and I am using a large sheet of freezer paper to create a rough size comparison for how large the base size on the ATV rack is. That way I can start laying out how big I want the base of the box I am building to be and start working on sketching up designs based on that size.

I have a good idea what I want the box to look like, so I just have to build the designs for how to cut the wood and get those measurements all figured out, then I can get some wood for building the box and start building it up.

Hmmm... I wonder if my nephew still has that old remote controlled ATV we got him several years back. I could create a scale mock up using balsa wood. Need to find out about what ever happened to that thing, if it's kicking around somewhere still or was thrown out over the years.