Good luck to you. Here are some thoughts: One thing I would want in "an uncertain situation" would be something I could use "off the grid." So I might go for an affordable flash player that used AAA or AA batteries. Now, it might be that you would have greater access to USB charging and "wall socket/mains" charging in the course of your work, in which case maybe a flash player with a built-in battery would actually make sense (maybe rechargeable AAs or AAAs will work out for you, maybe not).
To cover yourself, why not
both -- one flash player with built-in battery and one that uses AAAs or AAs? That way, you'd be covered in an array of eventualities. Plus, if something should happen to one, you'd still have the other. I don't know if this is the time to put all your resources into one "fancy" flash player (what if it breaks, is stolen, etc.?). But that's just me.
I just work in a cubicle in an office, so my situtation is quite different ... but I always like having a solid, functional 1GB Creative flash player with me, in my pocket or briefcase. In your case, the U-10 could be something of a stretch -- if you also have the Creative Vision:M, consider something relatively simple as your supplemental player. Would you really need the video capability in your smaller-capacity player? (I admit the U-10 looks fanatastic.) Just trying to be pragmatic -- but you're the one who has to be there. (You can really splurge and get a 512MB Creative, Sandisk or other flash player as your "back-up-back-up," and then induldge yourself with
both the U-10 and the new Vision:M
... you no doubt deserve it.)
As for the canal phones, be sure to take the (relatively undesirable) bundle 'phones with you as backups, in case something happens to your main pair. Or even consider taking two "good" pairs instead of just one "excellent" pair. Whatever you decide on, there will be Head-Fi'ers concerned about you (and your audio gear).