Can a "battery pack" be formed by wiring AA batteries in series and simply wrapping them as long as the labels of individual AA batteries are clearly visible?

If you are asking whether you can wire the 8 AA 1.5 V batteries in series or parallel or a combination of both, nothing in the rules says you cannot. So yes, you can make your own battery pack, as long as the vehicle has no more than a total of 8 AA batteries and all of their labels that say "AA 1.5 V" is clearly visible.