I'm not sure that perception would exactly fit.
Basically the Johnson flat out is not going to tell you what you are after right now. And knowing the "what" the material is wouldn't make a difference in your costs anyway. Yes, he's keeping information to himself. He's a Johnson.
As far as what you need... He's told you the equipment needed for taking the samples is included, and the vehicle to haul said supplies+samples. There are only 6 people you need to worry about transporting, 5+1. He's also more or less stated that the Alzmer is responsible for and capable of sample taking with your assistance, but its something he can show you what he needs on the spot. It's everything else that you are being hired to do.
You've got the expected time frame (2-3 days, preference of 2). Given your knowledge of traveling, most of it is likely going to be travel time figure 60 km per hour, tops, where there are roads, less where there aren't. So just time wise its not a day trip even if its just driving for most of the day.