Not speaking for Portland, but they are fairly easy to reuse. In the past people have recycled them by whitewashing them or painting them all black.
Portions of the Gold Cup tifo was reused for the "Many Hearts - One Beat" tifo. Basically, flipped it over and worked on the other side.
not sure where to post this, but here you go http://www.sounderatheart.com/2014/...-traveling-to-san-jose-and-some-observations#
District Ultras, La Norte, Screaming Eagles @ DCU-Columbus 3/8/2014 District Ultras & La Norte @ DCU-Columbus 3/8/2014
Can't wait to see RSL's tomorrow, I hear it's going to be a whole stadium tifo. Game is on NBCSN, hopefully they'll show it.