The chance of rain this weekend is likely but probably not enough to worry you BUT it is the high country and the weather is what it is. As suggested you could drive Cynthia Range and avoid Herne Spur as it's very steep and shaley in a few spots, Just go to the end of Cynthia range track and turn left at the bottom. I would not have any hesitation in taking mine along there and we drove the track only 4 weeks ago but we dropped down Herne Spur as we were not towing. Probably your biggest issue is tackling the oncoming traffic in the tighter spots.