It'll change the game too much... The best one I could think of to add to the game is another leader with "Team: Protect: Bonus". Mwahahahaha!!!
Of course, another idea is make a 1* for each clan. Lol.
Lastly, UR could also make cards with "-6 life to you" if the card got through. Lol. Of course, the stats of the card must be awesome like 8 power and 8 damage and it's in the rescue clan. Roflmao!