Not sure why you think getting a GPS signal is problematic at high latitudes? If I'm not mistaken, the GPS satellite orbits are inclined at about 55 degrees, which should give good coverage worldwide, including at the poles. People routinely use GPS everywhere in Alaska, with good success.

From GPS.gov : "The satellites in the GPS constellation are arranged into six equally-spaced orbital planes surrounding the Earth. Each plane contains four "slots" occupied by baseline satellites. This 24-slot arrangement ensures users can view at least four satellites from virtually any point on the planet."

You may be confusing GPS satellites with one of the communication satellite systems. Globalstar, in particular, has its satellites arranged in a more equatorial configuration. Getting voice or data links through Globalstar satellites has sometimes been a problem at high latitudes. This has been an issue for SPOT devices. While SPOT uses GPS satellites to get a location, SPOT transmits that location via the Globalstar satellite data link. Without a data link, SPOT can't transmit the GPS location, so sometimes SPOT doesn't work well at high latitudes.

Iridium sat phones has generally been better for high latitude areas. However, both Globalstar and Iridium are totally different systems from GPS.