We camp in a similar situation/way and through a serendipitous screw-up on my part I bought a 66 cell 185W high voltage panel intended for a grid tie system that typically puts out more than 38V at the controller. this required the use of a Morningstar MPPT controller which will convert the higher voltage to usable current. What this means in reality is that even in shaded camp sites we have some power coming. the big problem with "12V" panels is that any shading gets them below the point where they can put current into your battery. My panel will put out 17V under a full moon.
We spent 8 days on the north shore of Lake Superior in a camp site with maybe one hour of direct sun on the panel and at the end of 8 days we were at 64% SOC. The tear is set up for serious boondocking with all LED lights and we do not use any large draw appliances i.e. a french press substitutes for the coffee maker. But we do have a TV/DVD and XM radio, and the big power user is a 12V WAECO refrigerator (size and form factor of a large ice chest).
