Cakes that can be cooked whilst camping?
I'd look towards a dutch oven and cake-like items:


upside-down cakes
cobblers / crisps / grunts / bettys / slumps / etc.


In all of these, the fruit on the bottom helps to protect from the bottom of the cake-like-item cooking too quickly.  You can either cook directly in the dutch oven, or drop another pan inside the dutch oven to speed on cleaning if you're going to be cooking a few of 'em.  

You'll also want to look for dutch ovens that are made for baking -- they have a lip on the lid, so you can put coals on top and pull the lid without the ash falling into what you're cooking.