This is awesome! How did you manage the Enemy AI? I tried doing a spaceship game with Navmesh and had a lot of problems getting it working with vehicles that have a turning radius.
Well having no environment collision to avoid helped ;) But yeah that'd be a tricky problem to solve with navmesh!
I did have a bit of code to steer them away from on-coming collisions, but it was really pretty basic tbh, they just steered toward their target and accelerated when facing it.