My low level vents are ducted to bilge , behind the linings, from the front cabin bulkhead (approx 8 inches above the front deck) instead of being in the front doors.
All my ballast sits on blocks and there is a two inch air gap above the ballast with all the floor bearers running down the boat.Appliances like cookers/ fridges have air holes cut directly below them into the floor so constantly draw up the cooler air. Copper central heating pipes are run at floor level (but open to the bilges) and also draw air from the bilges when the heating is on. Been like that for some twenty odd years now and I have to say the bilges are probably the best bit of my boat and the only bit thats better than younger ones!