I've been in Deep Springs a few times. Are you referring to Deep Springs Lake? That lake varies in size quite a bit but does have springs running into the "lake" year around. Therefore the salt flats are probably not drivable in all areas, even in very hot dry conditions. Like the Bonneville Salt Flats when the ground is at all wet it's a nightmare to drive on so be cautious, even if it looks dry. There are roads that run out that direction though if you're interested in having a look.