I am very sorry to hear of your misfortune. Sadly, you are going to have to remove everything to get at the insulation and under the floor. The sooner the better if you can get at the mud before it sets it can be rinsed out. There are several threads on removing the fridge. The bathroom is assembled out of fiberglass panels and each can be removed. Remember what makes an Airstream unique is that everything in it has come in through the door. That means it can go back out the door while you clean and then come back in again. Good luck to you.
1994 30' Excella 1000, Chummy III- Ford Excursion- 7.3 Turbo-diesel