Really dig this idea!
Yeah, SHAR's combat isn't it's strong suit. While it's good it's not the primary focus for the game since it's a little underwhelming, it's also unfortunate the kick only really gets used against the wasps. There's also the coupling objective, though this never comes back after it's introduced. It feels woefully underutilized when more obstacles/kicking usage would've been great to see.
The idea of a secondary enemy type, while not possible to create due to current limitations (and might be difficult to replace the wasps with entirely given their animations and the way their model is handled), would be cool to see utilized in a mod for potential enemy car AI!
Sketch is cute too. Upvoted because I like seeing discussion about how SHAR's plot talks about other potential antagonists (such as Bart mentioning 'they' gave 'us' more cola on that spaceship) but we never really get to see that.