I found a soft spot, maybe 16"x16" in the garage area of my 2011 Model 3010 Cyclone toy hauler. This area does not get any traffic. There is a "D" ring in the center of the area and appears to be unaffected. I actually just used the ring to tie down my motorcycle for a 1,000 mile trip. The area is in the corner near the rear entry door and shares the wall with the kitchen. The area in front of the door is unaffected. The refrigerator/freezer is on that wall. I removed the drawers under the refrig and sink and all appears solid and fine. We bought the rv used in 2015 so do not know the entire history. I looked underneath and the black covering is intact. We never use water to clean out the garage, only blow it out. There is no direct evidence of water damage, but the "D" ring does show rust. I use a local mobile rv repair man and he said until he starts to work on it, he won't know what he will get into. He said it could cost between $1,000-$3,000. One other note, the spongy area is directly behind the rear axle/wheel. Only other thing I could think of is water from traveling in the rain? Any help on how to proceed would be appreciated.