Clan jacket is a very good idea, but you know, we have about 15 clans now (in the clan thread in docks, I'm afraid there are even more), in every clan there are men and women, pilots, engineers, gunners and multiclass players, and all the classes usually have different costumes (and I think clan items should be different for the classes too). It's about 70-90 different new items with 6 different models.
Also there is one more problem: clan members usually play a lot with another clan member, I don't think a lot of players will ever see this jackets. Of course in the adventure mode with walkable cities the situation will change, but I'm not sure we need clan items right now.
I think I also have a good idea, but I'm afraid you heard it million times before me. How about a painting on the ship? Somewhere on the balloon (there are few plain surfaces on the hull, and tha balloon is often bigger) we can put an emblem of a clan. There is a lot of free space on balloons now. Everybody will see this emblem through their spyglasses and become paralyzed with fear, they will be often seen in usual matches and maybe it will help with recruiting.