Thanks for all the great suggestions and responses.

Mac - are your 2 x 12's set up like this?

-----------------------------------
XXXXX-------------------XXXXX
XXXXXXXX----------XXXXXXXX

....disregard the X, that's just air. It's the only way I could get it the lines in that pattern to display!

If you have a pic that would be great, any setup that can put an FM on an open trailer without much work, storage issues, or money would be great.