By the same token, what's the likelyhood of multiple Divisions being based on the same world, so that one could afford to have all the Level V's fighters while the others focused purely on ground warfare? While I think the idea of assigning fighters directly to companies or battalions is among the more ridiculous concepts of BT military organization, any ground force of significant size, reasonably expecting to encounter enemy action, is going to require some form of air support. The modular nature of ComGuard forces certainly means that, should three or four Level IVs get together to assault the same target, they could very easily combine their aerospace assets ad hoc into an all-aero Level IV which operates in support of the other Level IVs as a whole.
I suspect that, pre-Clan Invasion, ComStar pretended it didn't have much in the way of AeroSpace assets, as it's much harder to argue that they're required to defend HPG stations than infantry, armor, and 'mechs. So while I can see the fielding of Level IVs without (or apparently without) aerospace assets pre-3050, I don't find it likely that any would exist post-Tukayyid, unless multiple Level IVs were grouped & deployed together.
