It is a very interesting question and subtly different than the much more commonly asked question which is how accurate is GPS, or what method provides the greatest GPS accuracy. Your question instead is about verifying that the location result that your GPS receiver has calculated is accurate.
To answer the basic question at least in theory, the answer is yes because a GPS receiver calculates position and time simultaneously as it solves the (x, y, z, t) problem. So if you are able to verify to the nanosecond that your GPS receiver has correctly calculated the time, then the position will be accurate also. A corollary question would be is it possible for a GPS receiver to calculate the correct time while meanwhile calculating the wrong position. I don’t know how that would be possible so I would say the answer to that question is no.
The challenge however is how to implement your solution of using time to verify the location accuracy. Your WWV example introduces a practical aspect to your question, although I don’t know if that was the intention of using that example. The constraint on the solution depends on what definition is used for practical. At the far extreme of practicality would be to use an atomic clock to verify the accuracy. However just purchasing or renting an atomic clock would not be enough as you will need some type of interface between the atomic clock and the GPS receiver that can compare the time difference between the two and display the result.
However even an atomic clock solution will still probably only be able to verify location accuracy within about five meters or so. This is because the GPS system uses GPS time which is not based on the Earth’s rotation like UTC is, so it does not include leap seconds. That in itself is not a problem because the satellites broadcast this difference in whole seconds so that GPS receivers can make the adjustment (I think the current adjustment is around 10 seconds). The problem is that GPS time is maintained separately from UTC time, and there is a process of “steering” GPS time within the GPS system to align within whole seconds of UTC. But this steering process is estimated to be accurate to only within about 14 nanoseconds (1). Light travels one meter in three nanoseconds so the discrepancy between GPS time and UTC would create a potential error of about five meters if using a UTC based atomic clock to verify if your GPS location is accurate. However if you are able to obtain an atomic clock calibrated to GPS time then you could verify position accuracy at the submillimeter level, which certainly will be accurate enough for whatever latitude/longitude decimal precision that your GPS unit outputs.
If there is a constraint that requires using a method less elaborate than using an atomic clock, then the ability to verify location accuracy is going to decrease dramatically. Using WWV for example will be much less accurate since WWV is only accurate to 100 nanoseconds, or about 30 meters (2). And even that level of accuracy requires that you somehow know your exact distance from the WWV transmitter, which is something of a catch-22 since in fact your exact location is what you are attempting to use UTC time to verify. In other words if you used the GPS location output to determine the distance to the WWV transmitter, then if the location is inaccurate this will give you an incorrect WWV time.
If you attempted to use something like Network Time Protocol (NTP) to obtain the exact time, that is only accurate within tens of milliseconds, which would not even help you verify that your GPS has you in the correct part of the country.
Although it is outside the scope of your question, the only practical solution is to use other methods to verify your location instead of using time. Using other methods you can get at least as much accuracy as the 5 meter accuracy that you would get using a UTC atomic clock. For example you could use a high-end geodetic grade GPS receiver. These will be in the several thousand dollar range, although presumably far less expensive than renting an atomic clock. These are typically referred to as GNSS systems (global navigation satellite system) because they are multi-frequency receivers which use more than one of the available satellite systems, GPS, Russia's GLONASS and Europe's Galileo systems. And you would want to use a high-end GPS antenna to help eliminate multipath reflection (like from other planes in the boneyard).
However just using a high-end GPS receiver still requires having trust in the equipment, which does not meet the spirit of what your question is asking, which is verification. A better solution to meet your criteria of verification, as well as achieve maximum accuracy would be to use an RTK system (real-time kinematic positioning) similar to what is used by surveyors. With this type of system you would place a base station transmitter at a precisely known location, such as the roof of the hotel where you are staying, or maybe a nearby gas station if they are amenable to this. The base station needs to be located no more than about 10 miles from the boneyard. At the boneyard you would have a mobile unit which communicates with the base station via UHF. The two stations compare the satellite signals that they are receiving and the mobile unit uses that information to make corrections and further refine the location accuracy, in some cases to within centimeters if you let the process run long enough as it will gain accuracy over time.
The reliability of RTK systems is possibly due at least in part from using the principles of Common View GPS Time Transfer (3).
(1) GPS time vs. UTC gpsinformation.net
(2) How accurate is WWV time www.nist.gov
(3) Common View GPS Time Transfer tf.nist.gov
RTK stations
(Author: TS Eriksson via Wikimedia Commons, CC BY-SA 4.0)
RTK mobile station
(Author: SparkFun Electronics source: www.flickr.com via Wikimedia Commons, CC BY-SA 2.0)
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