As per the suggestion of Alibi Editor Steven Robert Allen, we purchased an inflatable beach ball at the grocery store before heading out on our trip. The nighttime beach ball-fueled antics lasted into the early morn and provided a pleasant reminder that physical activity shouldn't be perpetually avoided.
I would encourage everyone out there who has even the vaguest interest in camping in New Mexico to make the journey to White Sands. You can camp in one of 10 designated areas within a two-mile loop inside the Park. It's first come first served, so you should show up a little early to claim your spot. It costs $6 for each person 17 and over, which includes the camping fee and the $3 entrance fee. Those under 17 can camp for just $1.50 with free admission. White Sands is generally open seven days a week but is occasionally closed for missile testing. Call (505) 679-2599 for more info.