I am very happy with the bra I bought from Go Westy (~$100).  Fits
perfectly and goes on and off in a minute (after the inital install).  It
uses covered metal tabs that hook around the door openings and elastic
straps that fit over the wipers and antenna.  I take it off whenever I wash
the van.  I don't see how stones would get behind it--it fits very tightly.
Install it on a hot, sunny day.  It's too bad it wasn't installed from
new--I also have chips from stones.  The front ends do take a beating.
                                                        Jay
                                                        '85 Westy