The second shot is going to have to count.
Thats a completely different story if your in that situation.
Re the use of METAR QNH, if there were any changes to be made to the AIP accommodating its use, I don't see why its use couldn't be allowed (if the changes were made) so long as the METAR issue time is within 15min of your arrival.
Or, increase the frequency of issuing of a METAR to say every 10 or 15mins. Problem is every man and his dog will be requesting the latest METAR from ATC.
But then if you have NAIPS on your smart phone, you could get it yourself. But if you've got phone coverage, just call the AWIS.
How many aerodromes are there without at least a phone AWIS?