Temps shouldn't be an issue at this time of year. These motors aren't nearly as finicky as nitros due to the flywheel blowing air over the head. There is a massive 1/5th scale dune running group in India and Pakistan, and it's a lot warmer there. They run bone stock and modified cars.
The main issue with running in sand will be your clutch, air filter and carb. The clutch can get some particulate in it if you're running an open clutch, which you are, but it won't kill anything in the short run. If you're thinking of hitting the dunes often, running an enclosed clutch is recommended, but by no means required. Just do some clean up after your run to determine what kind of mess the dunes will cause in that bell.
The air filter will pick up a lot of dust. Make sure you grease the seat where the filter is touching the base of the mount. This is more important on the HPI filter. The carb is also going to attract a lot of grit. The part to be especially wary of is the air hole for the diaphragm. It can collect sand particles and cause excessive stretching on the diaphragm, leading to tuning issues over time. Team chase makes a filter for the carb, but if you plan on running the dunes a lot, you can just cut a tiny piece of filter foam and stuff it in the hole under the primer bulb mount. Sand grit will also cause excessive wear over time on the carb throttle arm. There are some o-ring mods out there that will reduce this wear.
But in reality, just one day in the dunes will not wreck your car. Just give her a good cleaning when you get home, and have a freaking ball!
