@Miserys_End This is a lot of assumptions isn't it. Fact 1. It was said this is an only resupply camp for miles. Fact 2. Evil organisation has helicopters, which makes it easy to track a large convoy of cars given they move together. I can also make an assumption that if they had half a brain they would leave someone to spy on their actions just in case.
In any case in my original comment I disagreed with the "half truth" method for this particular scenario and I still think it is the worst one to take keeping the safety of the camp in mind.
Letting them know that you have seen the guy, but trying to mislead them is plainly disadvantageous and just putting yourself in more danger for no reason whatsoever.
When the bad guys leave they can still pack up and evacuate for more safety, but that wasn't the point of discussion.