This is the car I built and the way I build all my cars.
A slim wedge, 3 wheel rail rider, COG 1" in front of rear axle slot, 3 wheels with less then .003 out of round, BSA axles prepped from Maximum Velocity, Novus 2 polish for bores, Liquid Glass for bores, Hob-E-Lube graphite for lube. I used 3/8" lead rod for weight in this particular car. I often use 3/8" tungsten cylinders. I bend the nails for 3 wheels 1 1/2 degrees. I use the right front wheel for the dfw. The left rear wheel gets spaced .030 and the right rear wheel gets spaced .060. The dfw gets spaced 030. after the test board. Car is set to drift 2" in 4'. After running against the timer the car drifts 2" in 3'. I glue in the axles with Loctite Super Glue Gel. I know what you're going to say but I do it anyhow. I do not narrow the body of the car behind the dfw. The right rear wheel will stay off the rail by about 1/16" when running down a Best track. That's my build and it has been very successful racing under the Scout Commodore Perry District rules.
I know there has been a lot of talk about bending, not bending, rear axles. Here's my opinion. With a bent axle you have absolute control on how those rear wheels are going to perform. If you simply can't bend them you can buy them from Maximum Velocity. You can buy all 1 1/2 degree bends if you prefer. You can also buy preferred numbered wheels.
Best Wishes in your building and racing these little wooden cars.