There is usually a south westerly wind at CU. In my experience of flying SAR missions out of there I found the North coast normally had a higher cloud base due to the effect of the land lifting the cloud base sufficiently enough to allow an approach into Newquay. I have diverted into Newquay on a number of occasions having failed to get in on a PAR to CU. Yes there are several runways but they are not all down to 150 feet DH. I have no proof to hand that Newquay weather is better than CU, just my own experience. If I had a choice I would move the future SAR base to the North coast and use a new ILS into Newquay and/or pay the civy ATC to man out of hours.