Most women who have done full challenges end up feeling that it wasn't enough cardio. I'd go ahead and do more on Upper body days, but not HIIT.
I really don't think that a BodyPump class can substitute for an upper or lower body workout in BFL. BodyPump uses lower weights and higher reps and is a full body workout. Yes, you can get a good workout, but it's not the same as lifting to fatigue. I'd mix up your cardio and don't worry about doing extra, but if you are doing BFL, stay with the weight workouts. Otherwise it's not BFL
Mel