Use iPad as output device without iTunes?
What you call anti-competitive is kind of the point of DRM -- if it could overridden by simply writing a new program, it wouldn't be much of a stopping point.

In any event, you don't really say except at the bottom, but the implication is that you are trying to watch content purchased from iTunes. Is that correct? If so, you may be much more limited. If it's not purchased content, there are more options.

Next you will need a way to essentially broadcast content to the device. For years I used Air Video. You need to download the app to your device to act as the receiver, and the server app to your MacBook to act as the, well, server. Note the above app does not support DRMed content, such as items purchased in iTunes, but it does support most everything else you can throw at it.

Then, while on the plane, you will need to set up a direct WiFi connection. On your MacBook, go to the WiFi menu bar icon, click on it and choose Create Network. Give it a name, choose a channel, and enable a password for it.

On your device go to Settings > WiFi and tap on your new network. Enter the password, and you should be able to stream content using the Air Video client on your iPad.