Stratix 5700 - increasing amount of ports

Im looking into fitting the new 5700 into some of our panels and im basically looking at what is the best way to increase the amount of ports from the maximum 16(20) without having to go to a stratix 8000, im going to have 1 L33-ER, 1 PV+1000, 1 Kinetix 300, 14 22-comm-e cards, connection to a grace port, and a connection back to our network, im not sure if having two stratix 5700 with a copper connection would be ok, or if connecting the two together with the copper/SFP gigabit ports would be a better way to do this, taking into account the cost of the fiber and also the SFP's

Rob