SamR I've done the sleeping in car bit, actually it was a truck, of course that was because I foolishly left the back window of my tent open the whole day during a storm...
My current vehicle is a Jeep TJ so I'd rather use my tent if I haven't built a trailer by then.
Catrinka there is Wabamun, Sylvan, Banff, Drumheller...
If we go towards the south we probably would have a better chance of getting folks from south of the 49th and BC. Drum would probably be easier to get co-ordinated and a bit less busy than Banff.... hmn hills or valleys?