Don't eat while using your laptop and you will keep it clean with a dust cloth and a mist of water. Eat while using your laptop and no vacuum in the world will be able to suck that disgusting filth from it.
Except for my smart phone, I don't really compute in the outdoors.
My go-to provider for keyboard covers is http://kbcovers.com (no relation except as a satisfied customer).
As the saying goes, an ounce of prevention is worth a pound of cure.