I have done 60 pts with 20 command cards/points and it worked just fine. However, I did on star wars minis maps which are much much bigger than the puzzle crap they want me to play with.
This looks fun!
Did you use custom deployment cards for the rebels? Did any of the other SWM maps work out for you? Did you also use custom objectives?
I'm trying to see if I could use some of the maps on http://starwarsmaps.blogspot.com/ for bigger skirmishes.