It's been a long quest, but I think I have a solution I am happy with.
Previously my choice of camp/stream crossing shoe was the Sockwa G4. Very minimal with quite a thin sole, but for 7.5 oz in men's size 13 they were the best weight/performance trade off I had found, but were not very good for stream crossing
Thanks to everyone who posted in this thread I was able to try a few other things, and make a significant improvement:
Vivobarefoot Ultra IIs, Size 47 – Really liked the fit and function but at just over 14 oz they were a sent back.
Croc Swiftwater, Size 13 – Again, great fit and function but a whopping 17oz per pair. They *are* pretty nice though and I have decided to keep them for Kayaking and banging around on the weekend, but they will *never* be in my backpack. I would recommend them for the purposes I mention.
**Winner** Vivobarefoot Ultra, Size 46 – Pretty much the same fit and functionality of the Ultra IIs but much lighter…8.7 oz per pair. As Philip informed us, the Ultras lack an extra measure of durability compared to the Ultra IIs, but as far as I can tell they are identical in outward design and sole thickness. As Dale mentioned in his review, the inner socks are the extra added bonus. At 8.1 oz per pair they make a great camp shoe which is very comparable to the Sockwa G4s but with a significantly thicker, more protective sole for only 0.6 oz more.
Hope some of this may help anyone still searching. The Ultras in men's sizes are getting pretty scarce, but a few sizes are still available from Amazon and LeftLane Sports. The Women's version seems to be easily found…try 6pm.