Camp Eagle has hundreds of beds onsite. Some are within a few seconds, some within a few minutes walk to the start / finish line, main race area, and dining hall.
You can choose from really nice hotel style rooms, dorm style rooms, hostel style rooms (where you just buy a single bed in a room of 12-24 beds), yurts, screened shelters, tent camping, and car camping.
The following price list may change (you'll have to check with Camp Eagle to be sure. But this will give you an idea):
You can also sleep at one of a couple hunting lodges / inns in the little town of Rocksprings. Although there's not much to do there, there is a gas station and grocery store.
Also Kerrville is a full on small city, with several major hotel chains, many restaurants, gas stations, etc.