Cooperative challenge missions

I'm the kind of person who plays .skate in solo, but unfortunately I have to do a co-op mission and I don't know who to do it with. 

The only solution for me is to join a group of people I don't know, but unfortunately the groups are closed and no one wants to join my group (which I can understand), so it's difficult for me to complete the mission.

It's just a shame to be forced to join a group of strangers to complete a mission.
I know it's one of the main features of the game, but I'd prefer to have the choice of whether or not to use this feature.