The plains aren't like the mountains; they aren't as easy to conceal within, nor do they have as much variation in terrain.
Even in the dead of night, any disturbance in the distance is easily noticed.
Not to mention the Chaotic Blade Association's outpost perimeter, which includes mobile sentries, vehicle-mounted searchlight towers, and patrol teams. Trying to approach the camp under their night vision eyes is incredibly difficult, and if they add thermal imaging to the mix, it's nearly impossible to hide.
The players could only crawl on the ground, waiting for each patrolling vehicle to leave before advancing a short distance. They moved back and forth in the low-lying areas, progressing at a painfully slow pace. It took them a full two hours to cover just a few hundred meters, and even then, they still remained quite far from the camp's outer perimeter.
