During transit: No bare hands-operation
Zoom in / out
Pan
Toggle between different modes of navigation display (map - arrow showing direction to next waypoint, )
Set wp at my position (and preferably give it a name that makes sense)
show/hide my track
Thanks.
I can suggest the following:
1. Zoom in / out - 2 volume buttons, they are large enough (alternatively, shake the phone up/down/up/down to zoom in, down/up/down/up to zoom out - the first move dictates the direction, others - confirms it);
2. Pan - tilt the phone for more than 45 deg to the direction you want to pan, then back to normal for a fixed pan step;
3. Toggle between different modes of navigation display (map - arrow showing direction to next waypoint, ) - Shake your phone vigorously left-right (along the short side) to switch the mode from the looped list;
4. Set wp at my position (and preferably give it a name that makes sense) - cover the top of the screen with your hand (glove/mitten/bare/your forehead - doesn't matter) to trip the proximity sensor and cause the WP registered on the map (optionally use the voice to input the WP name, or I can think of gravity driven keyboard if you so prefer - still better than the 5 buttons input of Magellan);
5. show/hide my track - shake the phone forward/backward (along the longer side).
Also we have in the reserve "turn the screen over (screen down) and back" and "slap it with other hand at one of its 6 sides N times" but these are less practical.
Would that work for you?