Protecting MDF for midgate install

[emgmutt]

I was wondering if anyone had any ideas for protecting some MDF from water. I am building a box for a midgate wall install. Also does anyone have any iteas on how to mount the wall to the truck?
Thanks

 

[ygmn]

FIberglass it.....

 

[docopharm]

Never tried it myself, but polyurethane like you use for hardwood floors should work.