Condensation is sometimes unavoidable if the conditions are right. Floorless shelter or not it dosnt matter, your sleeping on a pad anyways and that is a vapor barrier. When it gets cold, you will get condensation on the outside of your bag as well as in your tent. The only real way to keep condensation down is to keep air flowing. You should have a means to have air flow through the top of the shelter as well as the floor
A bivy is one way to keep your bag dry when theres unavoidable condensation, or to allow you to open up your shelter more. Some bivies will leave you even more wet though because condensation will bild on the inside of the bivy. Im just purchased an event bivy from a fellow rokslide memeber, im hoping that it will breathe well enough.
Another way is to fire up the stove and cook it off

Woodstove, canister or liquid fuel. Iv lit my dragonfly and ran it on simmer more than a few times to dry things out.
I also always carry a small pack towel with me. It weighs almost nothing and has alot of uses, including wiping condensation off my bag, tent walls ect.
ventilation is all you really need though, and thats the way to keep it from forming in the first place