I'm hoping he's brewed by now.
He didn't say how much he was brewing or what kind of fermenter he was using. I was just thinking of surface to volume ration for swamp cooling vs exothermic temperature rise.
Others have mentioned Saflager W34/70 yeast. Sure the "traditional" Octoberfest has a cool ferment, but the thing is that Lager yeasts have a much wider temperature range than Ale yeasts. Ales are more common in my opinion because their "ideal" temperature range tends to coincide with the comfortable range for people. My brew store operator called ale yeasts wimpy compared to lager yeast.
My guess is that as long as you don't get a huge temperature excursion during the ferment you will be fine. This is the kind of thing where one of those TILT hydrometers is really nice since you can see the internal temperature and gravity.
Depending on your solar capacity, your interest in technical tinkering, and your fermenter configuration you might consider a Peltier cooler also.