But it wouldn't have a pullstart, and so I would never use the car. A "better" solution isn't actually better if it doesn't get used.

The weight of the pullstart shaft is a few grams. One of the wheels axles weighs more. The pullstart shaft spins faster, but that just slows down acceleration, it doesn't reduce the top speed.

It isn't a waste of time because I'm enjoying myself and learning useful information. This is a hobby, not a job. Even if I wanted to do RC stuff for a living, my current job already pays me more than an RC job ever could. If I can tell myself that I made this little engine work as well as it possibly can, then I will be happy.