Mortar shells -- being round, relatively dense, and not terribly effected by relatively high G-forces -- are well suited to this lift method. This is generally not the case for ballistically launched gliders.
After thinking about this a bit, a fairing such as is used to cover the payload of a real rocket may be the way to go here.
In my ballistically-launched rockets, I was placing the airframe tube outside of the launch/pressure tube as is the standard method with stomp rockets. One thing I did notice is that with the weight of battery+electronics all the way forward, the fins could be remarkably small. I never attempted a launch with the fins removed entirely, but it is conceivable that this could work.
If this is the case, you could use something that is a combination of payload fairing and sabot, keeping everything inside of the launch tube. The fairing/sabot would keep things streamlined during launch, and then fall away at or shortly before apogee and wing deployment.
