You have had some good info given and some bad- unfortunately you won't know which is is which. I usually winter in SA, but didn't this year- you are so close to where I live down there!
May I suggest going to one of the feed stores down there and talking to someone there- they might be able to give you a name of someone who can help you. You don't want to mess with something that has that much strength, and a 'not real smart brain' if you are a novice. Riding alone- especially when a novice is not a good idea. The sandy lot is a big risk for the horse- especially an older one- their digestive tract is not efficient even when they are young- as an older horse, the digestion is compromised- the risk of colic is high- at his age, very possibly fatal.
I foxhunted on my TB mare until she was 25 years old- so depending on the horse, the care it has had all its life makes a big difference in what the horse can physically do.
Find out about the horse clubs on the south/east side of SA- even contact a 4H instuctor - they might be able to help you out. Do you know anyone who has a horse on Lackland AFB? Both active and retired are allowed to keep their horses on base- I don't know the specifics, but if you know someone there.... If you can be around some serious horse people that would help...
Sorry- but I would be insisting on the girl coming out after school to be caring for her horse unless it is just way too far for her to get there. Boarding a horse in SA is expensive- I pay $500/month when I come down there- per horse- she should really be appreciating what you are doing for her.

I hope you find someone to help you!

 

heck didnt notice where you were at only about an hour from me if need some help be glad to come down and do something

 

thanks rich, i appreciate the offer (sorry for the delay, i just saw this).

well, i've been working him and his ground manners are improving. My dad came out Saturday (he had horses for years, but its been years ago) and talked me into riding him bareback (didnt have a saddle out there) and......


he did great. his riding manners ( or whatever the hell you call it) are way better than his ground manners, and they have been improving. so i rode him around the back area for a while saturday, then on sunday rode him all around the house.

he didnt really fuss with me riding him at all. a couple times he acted like he wanted to stop and eat grass more than let me ride him, but i corrected him right off and he responded well. he neck reins pretty good. not great, but part of that is learning curve on my part im sure.

so hes saved from the glue factory (for now at least) . (just kidding about the glue factory thing)

 

Sounds like you are making the right steps. Keep with it and you'll be fine.