Cloudbase is not relevant for making a Precision approach, only RVR. However, it may give an indication as to when you may become visual. In answer to your question, yes you could make an approach and descend pass the outer maker. Once you are past the outer marker, all bets are off.
PS. For a DH of 350' (yech, don't you just hate QFE), the RVR would have to be significantly greater than 550M.