About the problem.
I think that Windows tries to attach the pagefile before it initializes SD card reader's driver. That makes pagefile unavailable at this time, so Windows creates a temporary one. This issue is unsolvable.
Is it a problem?
No, I don't think so. While hard disks are few orders of magnitude slower than RAM, SD cards are even slower. It means that your system would become really sluggish as soon as it starts paging, ie. when it's low on RAM - and you don't want that.
Moreover, SD cards have lifetime limited by number of writes. It's usually not a problem when they are used for file storage, but paging would kill a card very quickly, probably within few months at best.
Use SD card for storage and internal memory for paging, not the other way.
4It sounds at the time Windows attempts to create the page file, your external storage isn't available, if that's the case there might not be a great deal you can do about it. – Ramhound – 2015-03-04T16:12:45.827