This new build (controller required) has all level art in place, and also custom colours. You can cycle through colours with the left and right bumpers in the player select screen.

Here's a quick look at how I setup the player truck layers for Carpoon in order to have better custom colours. The white base layer image_blend is the only one changed, while the shading layer is drawn semi-transparently. This gives some more control over the controls while before a lot of them ended up black with highlights.

I put this off for a while because I had to tweak the nine different frames for the player truck. Now at least, the eyes are separate and can be animated or scaled more easily if I want to.