The standard cabins on the Sovereign are 119 square feet, which are among the smallest cabins afloat. RCI had the idea at the time that cabin size was of minor importance so long as their were lots of public rooms. They backed off of this philosophy on later builds and started making the cabins larger.
Untold thousands of people have survived a cruise in one of these 4-person shoe boxes, so it is doable. But if you can spare the money I'd get a second cabin.