Okay, I've had a few questions/suggestions, thank you. Let me try to clarify things a little more as to which areas most need help.
Here's what I posted yesterday, an out-of-scale drawing of where the horses live:
The red pipe fence is fine, I don't think they could damage that if they tried.
Here's a new drawing.
The areas bordered in pink are high priority, that's where they usually live. They always have access to the corrals, and if any of the two far pastures are open, then they also have access to the front pasture. The area bordered in green is middle priority, they don't live there as often as the pink area. The yellow pasture is low priority, they don't live there more than a few months during the year, and that is my riding arena so I think I'd just as soon not have that one be "hot," at least not unless needed.