Please keep us updated if you take this further, I'd like to see what you do with it.
Taking it beyond the hyperspace tunnel into asteroid fields sounds great. Capital boss ships could be really fantastic... (and recall if you will, how Starfox 64 shifted from an 'always forward' locomotion to an arena style against its bosses, where if you didn't circle back yourself it would auto-return?)
What about a battlestation that... isn't a moon? Maybe you could, I don't know, fly down a trench or something?
Another suggestion: Take a page from Galaga, and maybe one of your ships gets 'captured'/tractor beamed... then, if you can free it by shooting its captor, instead of rejoining the hand it was separated from, it joins the ship that freed it, doubling its firepower (either linking the ships together, or having it in the previously mentioned wingman formation, behind and to the left/right, programmed to not fire if it's forward 'wingman' is in line?)
Simply put, by making hands into spaceships, you have blended the imagination we all had as children with the agility of our wrists and hands to create a unique mechanic, and I say why not throw the kitchen sink in there when it comes to space battle?