So far as I know, the BLM does not have any regulations about not having arches over the gate. I don't see any reason why they would not be okay. I don't consider them any more dangerous than any other type of fencing. A horse could injure themselves in a padded rubber room. LOL. Even for a BLM, unless they lead, they best way is just to back up the trailer to the gate of the roundpen and let them run out into the pen. At that point, the arch would be too close to the trailer for the horse to hit and when you take him back out of the pen, he should lead quietly or be trained enough to be ridden. Plus, I think you have to have the arch thing for the gate to keep the other panels standing when you open the gate. If it wasn't there, the other panels could move or fall over when you opened the gate. Hope I helped. Are you getting a Mustang? If so, I totally want pix.
I tried to look for some, but none of them were tall enough...
I thought that the fence had to be solid? I'm probably wrong. I haven't looked at the requirements in awhile. I don't remember anything about there not being arches allowed either though. I don't think it would endanger the horse at all. I'd be more worried about him rearing up and getting a hoof stuck through one of the pannels...but that's pretty much any round pen.
I also want pics if you're getting a Mustang. They have a local Mustang Makeover here I just don't have the set up. Good luck :)
I don't know about the gate thing, but I did have this little gem of advice, lol...
Dreamer, my Spotted Saddle Horse, likes to stick his head through the bars of our portable panels. Then, he freaks the heck out because he can't remember how to pull his head out. He'll set back and shake his head and literally MOVE all the panels around. I've seen him turn our round pen into a cresent moon shape =/ its even worse if there is another horse out with him, because they'll bite his butt and kick him and he's too dumb to pull his head out, so he jerks his head UP and runs with the panels. VERY VERY DANGEROUS.
Needless to say, I don't put him in the roundpen unattended anymore.
I just wanted to let ya know about that. It has nothing to do with the gate, but could be a problem none-the-less =)
We have tube type portable panels for our round pen. There is an arch gate on one side and a ride thru arch on the other. Our kids have never hurt themselves on the arches. Never try to ride under one that isn't designated "ride through" They are too short and there is danger to you more than the horse
Congrates on the BLM horse if your getting one