Bring a spare cable release. Two trips in a row I had to resort to triggering the shutter with a blade of grass.
You might want to consider a Mamyia 6 from the 50s, not the modern 6. It is a folder, 75mm coated lens, I can use S VI slip on filters and hoods. The range finder is somewhat small and dim by modern standards but useable, and you need to cock the shutter, other wise a very compact 6X6 camera. What is somewhat unsual is that the camera focus by moving the film not the lens.
Thanks everyone for your comments and suggestions - really helpful. I'm following a number on ebay just to get an idea of prices - seems there is quite some variability!
Chris' If you think you could work with a scale focus unmetered camera recommend a Perkeo 1 . I paid like $50 for mine and it is fun to play with 6x6 and fits in your pants pocket folded. I will say I tend to use my k mount Pentax and pentax 645 but the little perkeo is just fun.
Any Ensign would suit, but look for one that uses the lovely Ross xpress lens, I have 4, the Commando with a built in rangefinder and the ensar lens, selfix 12/20.820 and 16/20, all with the xpress lens, then there are the Ikonta's, the Ikonta B can be picked up for peanuts, another exelent folder is a Blda Super Baldax, with built in copled rangefinder, and I am only making suggestion's from my own collection, all of which I use and take fine negatives.