Use option-arrows with Unicode Hex Input
I've disabled the ⌘+⌥+space shortcut for Spotlight window (since I never used it anyway), but enabled the same shortcut to switch to the next input method. (You can configure this in the Keyboard preference pane.)

So whenever you need to use the ⌥ key to navigate, you can punch the three keys, do your navigating, punch them again, and be back in Unicode mode (if you only have two input sources; otherwise you'll cycle through them.)