A cubic meter of helium can lift about 1.1 kg at sea level, and hydrogen manages 1.2 kg. So if your airship gondola weighs 10 tons, you need 9000 cubic meters of helium, never mind the weight of the envelope that contains the gas. So that would make your envelope something more than 100 m long and 10 m across.
There is lots of steampunk art where the gondola is as big as or bigger than the envelope, but it really needs to be an order of magnitude smaller. Have a look at this real airship.
Real airships are these preposterous huge things. Steampunk art airships look like fisher-price toys to me. And having a huge gas envelope makes you very fragile in combat. The only time zeppelins were somewhat successfully used in war was in early World War One, where the Germans used them as bombers. This worked only because the planes of the time couldn't get high up enough. But a zeppelin versus a plane is no contest: it's a giant, fragile target. No fun for a game about fighting.
So instead the game uses Suspending Disbeliefium: partly because I wanted more of a weird-science dieselpunk ironclads-suspended-in-midair look, partially because I have a particular dislike of fisher-price steampunk zeppelins.