look at the frame
I'm pretty sure a 2.35 would work on the rim, but you really need to look at the frame clearance to see how much extra width you can fit in there. The front forks usually have more clearance than the rear stays. Remember that tire width numbers vary between brands.
Also, you may also want to look at a more flat profile tread pattern rather than a round profile tire. I know when running a rounded semislick on the back it felt like the wheel gained 50 pounds in the sand. I don't have any tire suggestions for you, as I just bare through sand with my currnet tires for hardpack. You may want to give it a try with your current tires as the 2.35 will have more resistance and weight that will be noticable off the sand.
Have fun cleaning out your shoes!