They aren’t very tall once put in the ground, and if you have to do corners you’ll need to rig up bracing or use a single T-post. But if your fencer has a really good zap, and your horses respect electric tape & aren’t the sort to just blithely jump fences to get where they want to go then you should be ok.
My guys have been behind this fence for several months now as my barn was being built. At first I needed to fence them away from the construction area, and now I’m using it to make sure that where I currently plan on putting real fence eventually is actually going to work.
I’m in the sandy part of SC, and I’ve not had any problems with the posts standing. I have them about every 8 feet though, and the tape (Zareba from TSC) is pulled pretty tight. It held well through the wicked storms we has a month or so back. I used short T-posts to anchor the ends and beef up corners, tying the step in to the T-post with zip ties. It’s not the prettiest fence, but it’s worked well so far.