I can't imagine needing A/C at Glacier NP at all. We went playing in the snow at the trail above Logan Pass.
Apgar heavily wooded. St Mary's less so.
While it can get to 90, average August temps high are 78 and lows..46.
2012 Honda Ridgeline
2016 195 RB.. 10,500 miles under tires as of today.
Been down many a dirt road in the west. We go where not too many rv'ers go.