There is some conflict here....
"Don't think I will take it into the house but hide it in cab of truck"
"when their away from their truck it is getting robbed."
Before I say anything else, if you take it, keep it on you! Nothing like someone saying "Oh my gun got stolen." You'll have a hard time saying that to whoever gets shot with it, which might be you, if you walk out while they are in the act.
Now... I need to say something for record, just to put it out there. I grew up in and around all white housing projects around Boston. I only say that, because it is NOT race. It is poverty, and desparation that makes those neighborhoods bad. And its obvious to the punks/dogs on the street when someone comes in from outside to those neighborhoods. Not for any other reason that they can sense the fear in people from outside, and see it as disrespect in a short calculation. So if you don't feel comfortable going there - don't go!
I have also worked in some really harsh areas of SF, and E.Oakland CA in my service work days. And people really appreciate the fact that you even came out. They know many people wouldn't bother parking the truck, after having a crowd of 17 year old kids mob around thier truck saying, "Check out the Cracker, he's lost!" They may have had other guys turn around and not even call back. It doesn't phase me because I have 30 different answers for that. And when I get to the address, half the time it is some older couple, and they'll post a nephew or someone to watch my truck for me. Did work for a church in E.Oakland, and they posted a kid at my truck for 3 days, after having a bunch of other contractors never show up. I didn't even ask.... But if you want, call your customer, and say, "Hey, no disrespect, but its kind of a rough area, do you mind having someone keep an eye on my truck while I check out the job?"