BLB,
Logically, I would think a large pot sunk into the ground and a deep layer of drainage gravel/rocks added to about 1/3 the depth of pot, and then only water from the top of the pot would also work if you're concerned about too much salt in your soil. Watering from the top would definately flush out any salt build up that might enter the pot from the bottom. But, for proper drainage you'd have to select a planting site that's on a slope for proper drainage, or you'll end up with a mud hole and a drown plant!!
Good luck!