Is it true that the "skid plate" is a piece of thick poly that attaches to the bottom of the tank? How much further does it hang down than the OEM tank?
The skid plate is a material similar to the tank, if not the same.
The tank sits into the skid plate as if it was molded to the tank.
It is nothing more then plastic, so I don't believe it adds any additional strength or support.
Overall the plate may add an extra 1/2" less clearence.
The tank sits about 2" or so lower then stock and is much longer.
I have never hit bottom with either this truck or the GMC, about 9 years of trouble free use between the two trucks.
With or without the plate, if you were to hit something, I would guess the tank would do OK. These tanks are tough, and poly tanks have been in vehicles since the late 70's. I would guess anything you were to hit that could damage the tank will damage a lot of other stuff on the truck as well.
Between the Transfer Flow and Titan, my opinion the Titan is a better option. For a given application the Titan is larger and I prefer the plastic over the aluminized steel.