Any tips/tricks from someone who dropped their crib mattress to the floor as an in between stage before converting to a toddler bed?

We have hardwood floors, so I think we would need to put some sort of area carpet below the cribs so that they don't slide (they have felt feet) if the kids have a tantrum and kick the walls of the crib.

I tried pushing the mattress under the crib from outside and it was too tight (which I think is a good thing. So I imagine I'd need 2 people - one to lift the crib and one to slide the mattress under whenever we change sheets....right?