I should probably get blitzed for suggesting this since I'm an American, but what about Carlos Bocanegra on a free? His impact on the wage bill would be negligible and at 33 he'd be a great bridge to give Baker/Clark more time to transition into a starting role. He certainly has more pace than Dunne, he still gets forward and can score goals, and sometimes plays RB for the national team. Here's the BBC story noting that he's been given permission to leave Rangers:
http://www.bbc.co.uk/sport/0/football/18865402
Since we're just throwing names out there I figured I'd throw in a slightly reasonable one.