here is a med weight retract servo http://www3.towerhobbies.com/cgi-bin...?&I=LXPB41&P=0 low profile at 1.2oz its a little heavy for a foamy but it will get the job done for sure.
or this one low profile http://www3.towerhobbies.com/cgi-bin...?&I=LXPB42&P=0