Not really advisable if there is any movement of valves you can get a herniation though the leading edge when you inflate. It's not big deal putting a bigger strut bladder in because the excess will be at the end of the strut so you can fold over. But you are going to have excess bladder both sides of valves that will connect to the struts. This will make lining everything up a ball ache and 2011/12 c4 are painfull enough as you have to get the bladder around a 90 degree angle as it is.
Get the right size from you local ozone dealer if they don't have in stock they can still order a full set from m ozone they take about 10 days to arrive