I don't consider myself an expert horse-trainer, or expert anything, actually. But I do have some experiences that I can share that might save Funder (and others) from learning lessons I've already learned (the hard way)!
So, let me write about keeping a horse contained in ridecamp.
When I started riding endurance, I rode Story, who could easily be kept contained by a fence made of masking tape. My riding partner rode Blaze, who could easily be kept contained by a really big pile of hay + proximity to Story. We used an electric-tape fence connected to a charger run on a bunch of D-cell batteries. No worries.
After a few years, I brought the Toad to his first ride, and put him in the electric-tape fence. He was nervous about being away from home for the first time, but he was parked next to his buddy and a pile of hay, so all was well...at first.
Around 11pm, a mare in the camp next to us saw a ghost (or a leaf...or a piece of paper...or an air molecule...) and slammed into her PVC-pipe corral. The night was cold, and the cold plastic exploded like a beer bottle tossed from a 4th floor window. The mare ran towards our horses, who ran away from her...dragging the electric tape for quite a while until it finally got caught on the tires of a rig several camps down.
They were in a fenced enclosure. The problem was, the enclosure was the size of Bellevue, WA (population: 130,000).
Our horses were gone. Gone. For 4 and a half days, they were GONE.
I assure you that you never want to hitch up an empty trailer to drive home from a ride.
They were eventually discovered by cowboys on quads who were moving cattle, and were transported home not much worse for wear. However, that ended the years of containing those horses with electric tape.
My friend tried some other containment systems, most of which were really freakin' heavy. Safe, yes. Toad couldn't break out of those things, and nothing could break in. But they weighed down the rig, they rusted like crazy, and they were an enormous PITA to assemble in camp after a long day of driving.
Friends of ours like Horses2Go corrals, which is not too expensive and not too heavy. I find the three-rail fence rather short to contain a horse intent on jumping out or bashing through. The company has a new 4-rail style that I think would be a better visual deterrant. I'm not convinced that the 3/4" square tubing will stand up to a horse who wants to throw his or her weight against it, and bent tubing easily becomes cracked and broken tubing. Not so safe.
HiTie makes a good system, but it won't keep out a horse who is running loose in camp. Since our mares are hussies, leaving their tailfeathers un-enclosed is not ideal.
The Spring-Tie system had some "attachment" issues a few years ago, which have apparently been fixed. (Horses were disconnecting themselves from the tie, and then wandering away. The hardware failure has been re-designed and I haven't heard complaints for several years...but if you buy a used system, be aware that you might want to re-configure the clips). Spring-Tie seems quite sturdy, but has the same tailfeather-exposure problem as the HiTie.
Here's a system that I like better: Hold Your Horses corrals.
They are tall, lightweight, and a good visual and physical barrier to a horse who is interested in escape but not determined to bash her way out no matter what. If a horse really wanted to kick the stuffing out of the panels, she could. So, not perfect, but pretty good for a cooperative horse.
Here's what I use:
The Silver Medal Panels were manufactured by a friend of ours in Oregon. They are square-tube aluminum, with diagonal braces for strength. Each panel weighs about 30 pounds, so a middle-aged librarian can move them around pretty easily. The rails are wide enough that a hoof will not get caught, narrow enough that a head won't fit partway and get stuck. A horse can jump on the top rail and it won't bend. The panels connect with steel pins and pegs that won't bend or break or disconnect the corral.
I can't recommend a specific product, but I can tell you what I've learned (the hard way):
* Know your horse.
* Visual barriers are important, and physical barriers are also important.
* Sturdy is important too, but if your corral is too heavy, you will hate it.
* That said: get something sturdier than you need...because not all the problems come from inside the corral.