First thing, I like the idea of using concrete reinforcing mesh for an inexpensive fence construction. I already have a 150 ft. roll I bought for just that, and a 50' roll originally intended for something else, but now fated to be fencing. Having horsed the 150' roll around, it's not exactly something you just unroll
Having unrolled some of the 50' roll to make a container for a compost bin, getting the one third weight roll to unroll was a struggle. The stuff does not want to uncoil and it fights back all of the time. Not to be discouraging, just forewarning that managing the wire requires some significant work.
I'm intrigued by your idea of getting the wire to support itself, rather than using fence posts. I had just been planning on cutting a bunch of posts, as our land is forest. Now, I'm considering your design pretty seriously.
Something I see as a potential problem is the low visibility of the tension/support wires. I can see a deer not spotting them and getting hung up because they misjudged their leap. This might injure the deer, and it also might knock that section of fence right over, depending on how much tension is in those wires. So I would plan on using something to make sure they see the support wires. String old CDs on them, aluminum foil flags, something.
My inclination would also be to stake the mesh down. The wire staples used for pinning down garden fabrics are cheap and might be sufficient. I have a few pounds of them sitting around and I think I'll see if they do anything....
The pallet idea isn't bad either, but I might recommend angling the boards. I think that would better distribute the load on the fence...
Something else I like about this concept is that it's relatively portable. Yes, moving 150' of remesh isn't a casual job and yes, the tension/support wires need to be anchored - but it doesn't require a dozen or more fence posts and detaching /re-attaching the fencing to the posts.
I'll need to chew on this a bit. In our case, there's another factor - all the trees everywhere. I can probably just nail the mesh to trees and run it wherever I need it off of them