Hi all,
Checking back in here.
SaintM: We walked down and camped at Horseshoe Mesa for two nights in May, so we were at the same site each night. My boyfriend got the permits in February or March, so you can use that as a guide for how far in advance you need to plan for a "back-country" permit. The permits for the main trail from rim to rim were not available for May in February or March. For those, I'm told you need to apply a year in advance, but I can't confirm that.
We ended up buying tents and air mattresses at WalMart after traveling out there from Virginia. The air mattresses were heavy, but well worth it. (We also had to bring a battery-powered pump.) We bought two tents and three air mattresses, with the others being for his kids and their SOs. One of the kids already had a tent. The pump worked fine for filling all three mattresses and also putting more air in the next day. One of the air mattresses wouldn't stay full, but we discovered that one of the kids didn't close the valve properly.
The tents performed like champs. These were very cheap, something like $18 each. They're two-person tents that fit the queen-sized air mattresses and still had room for our gear.
Believe it or not, in May in the Grand Canyon, we were setting up tents during a nasty storm. Rain, wind, and cold. In addition, the ground was so rocky and hard that the small posts that came with the tents would just bend when we tried to hammer them into the ground. We ended up putting rocks on the corners of the tent, which worked fine. In spite of a nasty storm that lasted for hours, our tent held up fine and kept us dry. I was seriously concerned that the top part over the vent would fly off and leave us with rain coming in, but it never did.
The next night we had another windstorm. The wind would blow hard for a few minutes, and then stop for a few minutes, and so on. The tent was bowing in rather dramatically, but again it held up fine. We were impressed, especially for the price.
We ended up paying to check a large bag on the way home with the equipment in it. Personally I hope to never camp again. It wasn't my preference in the first place, and now I feel like I've done my duty, but I would recommend the WalMart equipment. One of the tents has already disappeared with one of the kids anyway :-).