I am nervous about the integrity of the finished product if I frost, wrap, freeze, thaw, and unwrap. Can I freeze a fully decorated/frosted buttercream cake just in a plastic cake carrier---no plastic wrap? And then stick in the fridge before transporting?

yes — wrap the carrier in plastic is what you could do if you want— and thaw overnight in fridge

Thank you, K8memphis!

you’re very welcome!