So what if it doesnt have a long life on the field, I think it would be fun to field. I like the idea of it aiding artillery too. Though a balloon would be a target, arrows wouldnt necessarily bring it down. It would take a lot of holes to let out all of that hot air. I could see an eagle or griffin destroying it in seconds though.
I can imagine a ton of unique rules for this thing. A one time use pot of oil that you can dump and it has a small template effect and then the crew light some torches and drop them.
Also like giving one guy a hochland long rifle who gets slightly increased range because it will take longer for the bullet to fall, be useful for taking out heroes.
EDIT: OH and a really cool rule would be when it gets shot down, it can hit some modelsmaybe only a couple though, and it could have the rule of the mortar of 'Under the hole" or whatever its called because the big thing that makes the fire
And if it had explosives in it, then it would do even more damage. Or even if it just didnt get to use its pot of oil, then it would do a lot more damage.
Another rule I just thought of, Vials of holy water that the crew throw down if the enemy is chaos.
All of these things would of course have to be upgrades though.
I can see the basket being not too difficult, but how would i make a balloon look decent.