Are you are going to do something similar to War Thunder's "offline" mode? By that, you still have to log in, but they have a basic as spork campaign type thing where you shoot a bunch of bots in a series of mission types you can choose from. The only problem with their setup is you can only use what you've researched and bought so far, so no late war stuff unless you actually have something in that time period, which a new player would not from the start. It also has an extremely basic research gain that only lasts for the first mission or two, which would equate to like 5-10 perks here. It's mostly there for kicks or if you just want to shoot a bunch of stuff without the hassle one tends to run into in their online modes. I got tired of my G5N being intercepted by early F-86's and the occasional MiG-15 in main battle-modes...
In AH's case, a set of training missions with a few "offline missions" they can choose from after they've completed the training missions. Fighter Sweep, Intercept, Ground Attack, Naval Attack, Level Bombing. Each are pretty self explanatory and they can choose what to use, loadout's, etc. Maybe have them successfully complete each before allowing them into the arena's? No Air Spawning though for these missions though. They may take this as the standard for the MA, and when they go there and find out this isn't true, well...bad juju.