The dirt road to The Spiral Jetty is just fine, even when wet and muddy. Good enough to have driven a nice Mercedes 300D and a newer Corvette on. Not all that smooth but any vehicle can make it just fine.
If you give the folks at Northern Utah Camera Club a hollar or email they might be interested as well. Most live in Ogden and points North and a number have been photographing around the North end of the lake for some years now.
The two email addresses are for Gary Hurst and Barry Parsons, past & current officers of the camera club. Not a bad group at all and a number shoot LF gear. Speakers at their meetings in the past have included Robert Hall (on this board), Michael A. Smith and Paula Chamlee, Tillman Crane, Rodger Newbold, Craig Law and a number of other LF shooters of note.
Good luck on the outing. Great Salt Lake is a gold mine of photo opportunities for anyone with an ounce of creative vision.