Some of the answer to this question will depend on how physically demanding your job is during those 48 hours on. Sleep deprivation will have a big impact on recovery and just normal function. I recently read study conducted on ultra runners that determined that central nervous system (brain) fatigue had a significant impact on endurance performance. But one of the interesting things the study mentioned is that these runners can actually bank sleep so that during the sleep deprivation times they were not as severely affected. Might be worth trying.
As for the order of workouts in the 4 days off: I’d think that easing back to the training so that you first couple of days, till you get caught up on sleep are a bit easier training load wise and then saving the harder training days (either long or more intense) for the last 2 days.
I don’t think is going to one “right” answer for this and you will have to experiment to see what works best.