Why do you need to take a break? I work similar hours to you and routinely did back to back sessions 3-4 days per week in the last couple years of IM training. Typically, it was a 45-60 minute swim followed by either an intense 75min indoor bike ride or a run (often with some tempo or speed component to it). Or maybe a brick once in awhile. The key here is minimizing transition times (sensing a theme here?...you are a triathlete after all), but the good news is that you'll need less of a warm up for the second workout. I see people spending too much time screwing around before and after workouts anyway, and smashing two together is a good way for me to minimize that.

The only thing I noticed with this program is that since I was doing a lot of hard biking and running, every once in awhile I just had to back off the intensity of the swims, and they almost became warm ups for the other sport.