Adding speakers for extra volume should always be the first option, and a massive added benefit is the improvement in your tone when you have more cones working for you. That's why it makes no sense to paint yourself into a corner with small 4 ohm cabs.
I used to run 1, 2 or 3 Bergantino AE112 cabs, depending on the gigs. Same tone but adjusted to the volume of the band. Then I moved to a CN212 with an additional AE112. These days I'm using 1 or 2 BF Super Compacts. I'm happy to say that 2 SC's are easily matching the volume I got with the 3 x 12 rigs.
I've got 2 2ohm amps so I wouldn't rule out 3 SC's in the future.