Wet sanding and buffing is a total possibility with the flex agent in
the clear.
There is a window of time to get the job done, much like using Imron.
After that forget it--it's like sanding a brick.
I have a bra on the front end of my Van, and it doesn't even come close
to touching the paint with the flex additive in it.
The clear sticky chip guard stuff is a pain,expensive and looks like
crap.
I added the flex agent to all the paint on my Van--the wheel wells where
the stone's and road despise get's tossed around and onto  them don't
chip, nor does it scratch from sliding your ass across the top of the
door sill,and neither does the apron below the bumper chip or rock mark.
It all bounces off of the clear coat.
It's a tough product and works well for me--you just have to know how to
use it.
When are you going to finish the job on your Van anyway?
The top looks terrible in comparison to the bottom