I work 24 hours on, 48 hours off, there’s no access to a pool and only limited running opportunity, no treadmill, just some free weights and a barbell. Is it doable?

The biggest thing you will need is a pull-up bar of some sort to use at your station. Most of the workouts can be done with limited equipment. Also with the pool situation, I would recommend just doing the swim right before your shift and again after your shift, and a land workout in the middle of your shift. As long as you space it out like that and do all the reps/miles you will be good to go!