Hi,
I'm afraid there is no option to set a password for the patch. The patch is also saved in the showfile, so that wouldn't work out...
You can save the showfile though (Like I said, including the patch and custom fixtures) locally to your device. (iPad in your case)
If you press OPTIONS and press NEW, an empty showfile gets created. Select this, (rename it) and press SAVE.
You have now saved the currently loaded show locally to your device.
You can open it, and load it into the LPU by selecting it and pressing the OPEN button.
I hope this helps you!
Greetings,
Bootsy