Trash can a good idea- it provides privacy.
Get rid of the sand. Go get some dirt from your backyard or someplace where pesticides and fertilizer are not used. I don't know what the soil is like where you live but here in the eastern us, most dirt will already be the proper consistancy and moisture for laying eggs. This kind of soil smells natural and feels natural to them- you will have a better response for nesting than sand.
Fill a big trash can about 50% full of the dirt, add a couple branches to climb on, toss some dead leaves lightly over the surface of the soil- these will provide a natural cover that she will appreciate. you can also put an old piece of wood or a potted plant on top of the soil and start to dig out a tunnel for her about 3 fingers wide and about as deep as your fingers- angle it slightly down under the piece of wood or pot so the bottom of the pot or piece of wood forms a ceiling for the beginnings of the tunnel- this is also appreciated by most chameleons. Large dead roots and things sunk partway into the soil serve a similar purpose and some females respond better to these things.
