I'd always go with a short course of steroids to cover me over that kind of trip. But even then would still make sure that I didn't sit for more than an hour at a time - stopping and getting out and stretching or walking a bit every hour. If you have the dogs thats a great excuse to stop.
For the foods - cold deli meats, cheese portions, fruit, individual serve containers of tuna, salad veges, nuts, dried fruit. Also yoghurt (if I can get plain stuff without the thickeners in). I don't know what its like where you are, but I actually usually don't have too much problem eating no-starch when I am travelling, though I'm really low starch rather than strictly no (i.e. I don't test veges or fruit but just avoid the obviously starchy ones). i find I can usually get a decent sort of salad for lunch, or put together a lunch from some of the things I have mentioned above. For evening meals I just ask for the meat and veges and avoid potatoes, pasta meals, etc. Its actually easier for me as I am used to gluten free and having to avoid wheat based stuff.
