Thank you for your help! But what concerns me now is if they'll nest on the cage floor or should do so elevated off the floor and attached to the wall instead. I've seen them nest on the cage floor doing fine, though I'm worried this doesn't seem to replicate their nesting position. I do know some species breed on or near the ground, like ground-doves, but most choose not to.
They don't care. The cage is off the ground anyway... so they are not actually nesting on the ground. I hang my nest baskets on the cage bars.... so that no droppings fall into the nest.