Another thing to consider: Horses are herd animals. Most do not do very well mentally when they are alone. Thus far, you've talked about keeping ONE horse.
I never said anything about getting only one horse. I'm nailing down the costs for a single horse. Two or three horses will be two or three times that cost. Also our neighbors have horses, so they've got somebody to talk with.
Square bales are going to vary in size and weight. I think it would be quite minimal to figure 1/3 your "average" square bale a day. I would consider at least 1/2 square bale a day per horse, if not more. Yes it will vary on the weather (colder and they will need to eat more).
It's interesting that everybody in this thread is saying that my expectation was very low. Everything I've read said to expect 2% of their body weight, which, for a 1000-lb horse, would be about 1/3 of a 60-lb square bale. I can plan on more, of course. That's just not what I keep reading (even on this forum).
If your daughter wants to jump competitively, you are most likely going to want your own truck and trailer. Insurance and licensing is small potatoes compared to your purchase price of an adequate towing vehicle.
If she decides to compete, then yes, we'll surely get our own trailer. We've already got a fine tow vehicle in our Chevy Tahoe. It's rated at about 8000 lbs, and I frequently pull a flatbed trailer loaded to 6000 lbs. The used horse trailer would be the only added expense there. And again, I'm only asking about the ongoing costs, not the up-front costs.
I also routinely have my horses examined by a chiropractor. I've seen great benefits for their performance. Mine charges $60 per horse each time.
I've never heard of a chiropractor for horses. That's really a thing? ... Sure enough, it's listed as a service provided by our vet. Whadaya know.
Depending on how much you spend on a horse, you may want to consider insurance for the horse.
We're only looking at spending a few thousand for the horse, so I suspect that insurance isn't worth it.
This thread has been very helpful in filling in some of the gaps that I hadn't considered. Thanks, everyone.