In the picture..top left part of the parking lot, it looks as if they have somewhere you could drive on to the grass without the worry of hopping a curb. I've never been there, so I don't know if that is how it is. If need be, I'll drive there in a couple of days to scout any areas of ease to get on grass. I live pretty close so I don't care about the drive.
edit: nevermind, I forgot you said big grass area was for vendors