Best advice I can think of is DON'T shave your kees. koshmom
lists extremely vital points against shaving. I've lived with multiple kees for the past 12 years in atlanta, ga (moved from up north, so yeah, it was a bit of an adjustment) and here are the precautions I take in the heat (and humidity):
Carry LOTS of water.
Go early if possible.
If it's already warn before you go, make sure you stick to the shade as much as possible.
Feel the surface (pavement, cement, whatever) with your hand. If it's too hot, then that will just make your baby warmer.
BRUSH THAT FUR. Every day, even on days when you are not out walking, brush the fur. Work that undercoat so that air can circulate. Once your baby starts to blow coat (and they do, just maybe a little later than you would prefer), then spend even more time brushing that undercoat out. It will come out in cottony clumps, but that is less insulation your furbaby is carrying around.
Remember, a keeshond's fur protects against hot, cold, hard wind, and rain. Loosing that is like losing the outter (protective) layer of your skin.