Deve:
Your logic is sound. The dedicated gun that screws onto the bottle is simply a better approach to avoid finger fatigue. Sure, I agree the aerosol stuff will be the same quality...but probably more expensive. Do your finger exercises now to get ready.
Remember, Body Schutz is first and foremost a sound deadener. To me, there is no better place on the cab than the bottom to benefit from some sound deadening. I chose this route instead of the typical "dynamat" approach because I did not want the buildup and look of the "dynamat" under the rubber floor mat. When you lift my mat, all you see is nicely painted sheet metal.
Like you, the main reason to apply on back side of fenders is for some protection against inside to out stone dings. I think the rubberized quality of the Schutz will come into play in this situation.
Most vehicles of our vintage simply had primed under bodies. I suspect the trucks were no different.
Last edited by DavidF; 06/05/2014 7:29 PM.
