The liability I see is that you are altering it from its original design. Therefore if anything happens in an accident where they find the use of plexi caused harm to the end user. I could see it making you poor when the lawyers get their share of it. Im NO expert on plexi but would be concerned about liability of it.

It reminds of the same thing when people don't like convex passenger mirrors and want us to put flat ones in. We dont because it alters the vehicles original design. Plus its almost impossible to glue a flat mirror to a curved backing plate. I really ****ed off a guy one time because I told him I wouldn't do it. He can buy the mirror and do what he wanted but i wanted no part in the act of putting it on his mirror. They sell flat ones but that was not what he had on it..

I did find the comment of the use of plexi on camper shells interesting and will heed the warning there because we see it all the time and even know the plastic shops are doing it.