I would add the combo to an extension cab. However, it does not look like it has speaker out (from the fender site)
I would install an output jack, and rewire the 2 internal speakers for 16 ohms (they are 4 now, once again going by the fender site).
Find a good 8 ohm cab and plug that in. It will end up being a little over 5 ohms, so a little less power, but I doubt you will notice.
You could also run it to a 4 ohm cab, and just not use the internal speakers.