I usually keep the 'dorff & a bunch of holders in a hardcase, but decided I needed to travel light. I went into my local EMS (Eastern Mountain Sports), and found a bag that suited my needs. It was meant to be a cooler, so it has an inner and outer plastic skin, with a bit of padding between. The camera fits snuggly inside, and there's room to carry a couple of holders. The bag has mesh pockets in the lid and on the sides, so it's possible to pack a few essentials, e.g., meter, loupe, etc. Unless you're using a small lens, however, there isn't enough room to pack that. You should use a GG protector.
The only negative about the bag is it's price - $40. I'm sure, though, it's available elsewhere, perhaps cheaper. Keep your eyes open.
Charley