Government Trail is a good starting place for loop hikes with 1 car. Try entering Pollys canyon from the trail head, venture down pollys (plenty to see here, ruins and rock art, side canyons are great) to the gulch, set up camp, explore big man and the plethora of ruins and rock art (check out the rincon behind Pollys island). You could stay here a couple of days exploring, and then head back up the government trail to your car, or head down canyon a few miles to Deer Canyon, exit and cross country back to your car at Government trail. Other single car loops that come to mind: Sheiks canyon loop, park at the Sheiks canyon trailhead (past the Bullet canyon trail head), go down Sheiks and camp at Green Mask ruin maybe (a couple of fine camp spots here), head to the gulch and down to the intersection with Bullet. There is one of my favorite ruins about a mile down the gulch from here, and green house canyon, with one of my favorite pools (about a mile up). Head up Bullet to Jail House ruin, great camp spot in the alcove to the upper right (if you are facing the ruin), big beautiful cave here that also serves as the access out. From the back of the cave you can switchback up and out of the canyon, when you reach the ledge below the rim you kind of have to search for the final 20', with a little patience it is easy to get up on to the meas, cross country back to the Sheiks Canyon trail head. Sheiks is my favorite loop in the Gulch, the hike is not easy with a full pack, takes some thought to route find but is the most fun IMO. Step/Pine canyon loop is great too, completely different vibe here. I have done 2 loop hikes from Todie. Park and enter at Todie, down the gulch to Coyote and then up Coyote and cross country back to your car, or continue down the gulch to Bullet, up Bullet and cross country back to your car at Todie, Muy Macho!
Greg