Hi Ian,
I've been up and down Long Spur a few times over the years, the last time on my AAWT walk last spring.
There are no real navigational issues on Long Spur, I guess you 'could' go wrong and head down Mulhauser Spur but you'd pretty unlucky!
The upper reaches of Long Spur make for very nice walking but the lower sections can be a bit of a slog, unless you want to carry water for camp you'll probably have to go all the way down to Big River Saddle to camp, picking water up at one of the gullies approaching the saddle. Can I suggest keeping on going and climbing up to Mt Wills Hut, the views from up there at sunrise and sunset are very sweet and the hut is very comfortable - it has a tank although I'd probably carry water up from Big River Road just to be safe at this time of the year.
Here's a link to my AAWT post that featured Long Spur if you want to check out what things look like on the ground
https://goinferalonedayatatime.blogspot ... lpine.htmlCheers