> 12 hour rotating shifts, different days off every week, don't always work the same shift
Well, you're probably already doing it, but having a very functional calendar's important
Otherwise, you'd run your system as usual - process incoming when you're at your inboxes, decide action, park in appropriate organizing places (projects, action lists, waiting for, calendar), and work when you have time.
> your "office" is a car you may or may not be in at any given time
I'd say carrying relevant support materials is important. I recommend carrying the following:
o calendar
o actions list
o waiting for (optional)
o projects (optional)
o capture tool (i.e., blank pad/cards)
o Action Support folder (for actions needing paper that doesn't have a dedicated folder)
o Read/Review folder (for those "between" moments - only for FYI reading)
o relevant project folders
Contexts could be useful, as mentioned elsewhere. If your computer and phone are with you then you'll be able to do actions requiring them...
Finally, having clear collection systems is important, due to your varying schedule. Having a time to empty them (I assume some come into your mail slot or inbox in your building) is crucial.
Good question; I'd like to hear how you customize it for your work.