We put one in on the side of our house. Only our dog runs on top of it so I don't know how it would work with horses. Neither me or my husband is handy around the house and we put it in together. We went from having about a foot of standing water to bone dry all the time.
Maybe what they call "tiling" would be what he wants? Check youtube for some clips on how it's done, it's not as fancy as a french drain but similar. Used in ag fields so it can take wheeled vehicles, just not sure about hoof pressure.
We have one in our pasture alongside the (bank) barn. The horses are on it all the time with no trouble. It was a big trench (proably 6' deep and 10' wide and 60 feet long and they filled it with rocks then topped it with smaller stones. Eventually the horses sort of covered it it with hay/manure/dirt and 12 years later it's working fine. I use the tractor to scrape the mud off every 6 months and have to be careful not to dig up too many stones, but I'm a much bigger problem than the horses.
If it's just rocks like Hilary described, it ought to work pretty well with horses. Top it with cow carpet or landscape felt and then some soil if you're really worried about either horses on rocks or fines clogging your drain.
Tile, on the other hand, can have a lot of problems if you put livestock on it.