We have always gotten water in the utility bay when we drove in the rain. And I found this a real annoyance. Recently I discovered that the caulking had failed on the back side of the door for the sewer hose storage tunnel. When I removed the door a few weeks back to spray bed liner on parts of the bay (see photo) I was able to remove all of the old caulk and apply a thick bead of caulk around the door just before setting it in place. A week later I sent a heavy stream of water against the outside of that connection. It leaked. So I knew I needed to apply more caulking. The only problem with this solution is that it is a really, really tight area in which to use and maneuver a caulk gun.
Necessity is the mother of innovation. {Feel free to quote me on that.}
I bought a piece of clear flexible tubing at Ace Hardware. The inside diameter size fit tightly over the nozzle of the tube of caulk. (see photo). I decided to use a Liquid Nails product for roofs. I figured that roofs take a real beating and so does the area directly in front of the outer rear tire where the back of that tunnel is located.
I drafted the Cookie Queen to squeeze the handle of the caulk gun while I directed the clear plastic hose around the four side. A photo of the finished caulk job is included. It is not real pretty. I like neat work, but lying on my back and putting a nozzle where I could not see was a real bear, but we got it sealed.
Also, used the steel pipes between frame members as a safety precaution.
Another problem solved.