I flooded my new trailer in May, fortunately in Arizona. Fresh water. I took similar action, cutting it open underneath and pulling the soaked insulation. I let it dry and drove about a 1000 miles in dry weather with it exposed. A bit of water got under the linoleum near the floor vents, fortunately its not glued, I stuffed a pen under to let the air get in there. I also think I had some wet insulation between the floor & one tank, but some air can get into there even though I am sure it took long time to dry. I know it did not go beyond about a foot as there is a vent coming up from it further along where I could see dry insulation. I pushed a wood shishkabob stick through there recently and no moisture. I did do an insurance claim, most of the cost was replacing insulation and resealing the underside. I have now built an alarm system, and I have water sensors all over the place. Any moisture sets off a loud alarm and shuts off the pump
