It seems that every camping trip we go on, we end up carrying tons of stuff. Who knew that campground activities required so much stuff. We have a huge cargo area (known by RV'ers as a basement); the manufacturer calls it "Mega Storage". The cargo area is so large that items can shift while underway, so I decided to add some tie-downs (D-Rings) to the floor of the cargo area to facilitate securing the contents. The tie downs I am using are stainless, but I probably could have used standard zinc-plated versions as the cargo area is relatively dry.
I installed 12 D-Rings more or less equally spaced around the perimeter of the cargo hold. I did not add tie-downs to the center of the cargo area as I did not want cargo snagging on the D-Rings.
I oriented the D-Rings so that they could use a standard 4'x 6' cargo net or using bungee cords individually without the net. This gives me maximum flexibility in loading and securing cargo in the storage area.
Installing the D-Rings was a pretty difficult task as the center 4 tie-downs had to be installed into the frame, and the rear-most two tie-downs required standoffs to ensure the plastic bin did not crack. The 8 tie-downs on each side were almost as difficult as a piece of angle iron on top, and a square steel tube on the bottom had to be drilled through. All of this took time, and resulted in several broken drill bits.
I started out the drilling process with cordless drills, but had to eventually go to my Milwaukee "Hole-Shooter" (1/2" corded drill) to finish the job. As flexible as cordless drills are, heavy-duty drilling is not a good task for them.
The 4 center D-Rings were attached with machine screws and bolts, while the 8 side D-Rings were installed with self-tapping metal screws, as I could not get inside of the frame to attach bolts for these D-Rings.
One thing I found with the D-Rings is you have to grind down the weld of the ring itself or it will bind when secured to the deck.