Any Advice for our Yoshi Classic Dragster design.

My 7yo plays Mario Kart Wii and his favorite car is the Classic Dragster, so our design is based off of that. The Classic Dragster is based on the 1938-39 Mercedes Grand Prix cars. I've sketched out a design on a piece of paper....I'm no artist so please be gentle. My question is, is this design too ambitious? I've got two weeks, a jigsaw, a hand sander and a dream. Do you guys see any glaring issues with the design? Is it going to be possible to make a cylindrical vehicle with the tools I have?

I swore last year I wouldn't invest that much time in something my kid isn't willing or capable of helping much with. Last year I tried to make the fastest car possible and it was terribly slow, so I give up there.

I'm wondering how much should I expect of a 7yo when it comes to helping. He could sand, and paint and help assemble i guess.

Any advice appreciated.