Remember that their navy is reduced to a crippled Kunai, and one with an unknown amount of fire damage, and a number of out of position skiffs.
Whereas we have the Mongoose, which is still in perfect condition.
I propose that we have it try to run their Kunai's down. If we can finish off at least one of them then we've effectively regained air superiority, and cutting them off at their demispire would stall their repairs long enough for us to safely drop another set of reinforcements off at TC. Is it a bit of a risk? Yes, but to not pursue effectively puts the state of the air war back to where it was after our last major engagement: 1 Windrider for us, 2 Kunai's for them. Except now we don't even have a decent foothold on the ground. Except this time we have a pristine Windrider with better armor and maneuverability instead of a defensively compromised one.
(My confidence in re-attaining air superiority after killing another Kunai is simple: We've more or less proven the supremacy of an individual Windrider over an individual Kunai, at this point. Overall fleet numbers were 9(us) vs 8(them), with 7 skiffs vs 5, and 2 Windriders vs 3 Kunais. A Kunai is worth a lot more than two skiffs I'd say.)
As for the ground, fighting retreat tactic, use barricades meant more to stall than actually protect, do surprise MOVE PLACE strikes then immediately fall back to the next fallback point.
Should inflict decent casualties against them, and hopefully prove to us if they have any more grenades or not... If nothing else, it should ensure our continued survival until next turn when we can reinforce more troops, our PLACE out-ranges their grenades, all we need is sufficient numbers of them to cover all the flanks.
TLDR: Ground situation is really, REALLY bad, but we have a solid chance to turn things around in the skies!