Hi wizz, for western Canada, you've identified the "biggish" event in that timeframe, specifically the Sundre AB event. The only other event that I'm aware that hasn't been scheduled yet is Barebones which sometimes happens in June/July in Alberta, sometimes more towards September. It is really fun, & I hear it is generally pretty fine quality O....good luck, have fun!
http://www.barebones.ca/
OABC has a nice regional(+) calendar on their website...search OABC...
I think there's some trail running in the Vancouver area in that timeframe too...maybe squamish thunder (?), mount seymour peak challenge, which are non-O but interesting trail-based events - pretty locations, fun terrain...