If we can do the 180 seconds (big if) then I'm pretty comfortable beating the rumored 0.8m accuracy of Armadillo, beating the rumored 10cm accuracy of Masten is going to be a lot harder.
I still have a fair bit of work to do, but it looks promising. I'm not going to say much more about this as I don't want to give to much away. The chalange is in the vehicle dynamics, not the GPS.
Any sufficiently advanced technology is indistinguishable from Magic. Multifrequency RTK GPS stuff is sufficiently advanced. When you realize your making sub 1 cm scale measurements over a 20000km distance in real time at many Hz it is stunning. That is 0.00000005 percent. or 0.0005 ppm.