I would suggest using the rules for the Ice Guard!!!!
They are NOT like the Valhallans (who appear to be from a planet that is nothing but a huge ice cube)! They are from Luybov, which is a planet similar to Canada or the US Rocky Mountains. Sure is cold most of the year (and has snow!), but it has coniferous forests, mountains, etc... the Ice Guards are highly trained mountaineers and specialize in using the battlefield to their advantage (AMBUSH!!!)
Take a few minutes and read about them on TLRB... You could make the Officers GREAT snipers as their specialized harness will make them almost invulnerable to falls from higher ground (as well as aiding in climbing) and their ambush techniques are pretty brutal!