[watsonholms]

having the exact IP does not matter.
You need an ip that connects to a relay which is close to 30-40 miles from card holder location.
Maybe you can spoof the WebRTC and DNS to make it look like you are using the holders IP, to find it do as @lebowski said.
But you'll never need to have the EXACT same IP because 1) merchant don't have it on file 2) merchant will look only if it's close to card holder address ( look above ) and if it's marked as proxy 3) many routers and legit people dont have a static IP but a rotatory one, if you'd need to have always the same IP, every merchant would need to decline 60% of the incoming transactions and of course that does not happen.