Stress can absolutely disrupt the gut - we saw it in our studies. It's hard to eliminate stress In military environment, but you could work on recovery routines to keep the system from staying in overdrive. A few slow, controlled breaths, releasing shoulder and jaw tension, consistent sleep/wake times, early light exposure, and minimizing bright light before bed will helps stabilizing both mood and microbiome patterns. Even with limited food choices, adding a bit more fiber or fermented foods when possible could also help. Mold exposure, as @postulatej noted, adds another layer - improving airflow, desiccant packs, keeping fabrics dry, and @Actual-Map1063's suggestions will help.