I asked a few crawlspace waterproofing company came to look at my wet crawlspace and they all suggested a system similar to a french drain around the inside perimeter of the foundation wall. It would terminate in a sump basin (bucket) that contains a sump pump with the output connected to a storm drain.
Since the foundation is resting on soil, wouldn't digging a trench in the soil near the footing weaken the soil's lateral support and lead to settlement (sinking)? They would fill the trench with wash rocks but still it would not be as densely packed as undisturbed soil.