Let's assume:
- the white truck exists and is more or less as described
- the white truck belongs to the sniper
- the sniper doesn't want to get caught, at least now
- the correct truck has not yet been turned in by someone to the police tip line

Could the sniper be driving this truck around the general area on a daily basis?

Most likely not, with one exception. The description of the truck includes indistinct or so-far-unrecognized black lettering on the side. What if that lettering is just a red herring? What if, instead of being painted on the truck, the lettering is on a plastic card of some kind which is inserted into a bracket on the truck or is otherwise bolted to the solid white truck. Alternatively, the lettering could be on the truck (perhaps not fully painted over), but most of the time it's covered with a large plastic sign.

Let's say you buy a used truck which is painted with the name of some other company. To look spiffy, you decide to paint the truck, but you're also cheap. Because you know you're going to put a sign there anyway, you don't pay that much attention to obliterating the previous company's name, you just do a bad, quick paint job.

The sniper could put the letter board on the truck (or take the larger letter board off) just before committing an attack, and then simply reverse the procedure afterwards. Those who see the truck would notice that it didn't have the requisite lettering, and would assume it's not the truck that's being looked for.

But, for now, let's make the further assumption that the lettering is painted onto the truck, and it's not covered up by the sniper.

Could the sniper drive that truck around on his daily business, assuming that he has a job of some kind?

I don't think he could spend a lot of time in one area near the crime scenes, or regularly visit the areas around the crime scenes, in this truck without someone turning him in. The reward is very large and people are on the lookout for this truck. If, for instance, you worked at a delivery company with several trucks like this, wouldn't you examine them to see if one of them had rear body damage, or if the timing is such that they could have been used? If you worked at, for instance, a restaurant, wouldn't you pay special notice to the delivery trucks, or think back to what the trucks used by those who deliver to the restaurant look like? Even if you were going to employ a plumber for a very small and quick job, wouldn't you examine his truck to see if it matched the description? Even if this is someone who you've known for a long time, a half a million dollars can make people turn in even their own family members.

So, still assuming that the somewhat illegible black lettering is not usually covered over or removed somehow, I don't think this truck has that much people contact.

There are, however, a couple of exceptions to my supposition. One, it could be driven by someone no one suspects, or two, the writing could be such that no one suspects it.

In the first case, the usual driver of the truck could be a clergyman of some kind, or could be an elderly woman.

In the second case, the lettering on the truck could be for the rangers at some local park, or a university, or a church, or some kind of inner-city food program.

In either of those cases, people would tend not to suspect the truck.

That, I believe, covers the cases where the truck has a fair amount of contact with people in the general area of the attacks.

Alternatively, the truck could be used as a work truck, but it is only used as such in an area far enough away to avoid suspicion, such as PA or NC.

But, generally, I don't think this truck is currently used as a work truck. I think the sniper realizes it's important to avoid the truck being seen regularly.

If the truck is not parked 100 or more miles away from the general area, it's probably stored in an unobservable area with difficult-to-observe ingress and egress. Two such areas come to mind, both desolate: a very rural area with easy access to a crowded highway, or a deserted industrial area, perhaps right across from railroad tracks, a concrete sound buffer, a river, or some other natural or man-made protection from observation. For added protection, the truck could only be driven out early in the morning, and it could be returned after dark.

Where did the truck come from in the first place? Presumably, the police are cross-referencing MD and VA registrations. What if, for instance, it was bought in TX? The police most likely aren't checking registrations from out of the area. However, even if the witnesses aren't able to read the license plate numbers, surely one of them would have noticed that it didn't have the license plates that they're most likely used to. So, the sniper could have put stolen local plates on it, or switched the plates with another vehile to which he has access.

Alternatively, the truck could be a former work truck which hasn't been used for a couple years, and perhaps was registered as non-operational. The neighbors who knew at one time that the sniper owned such a truck would most likely have forgotten about it if they hadn't seen it being driven for a while.