***Caution*** I haven't tested this:
I've been reading up on a program for Lexar flash drives called BootIt that can flip the removable media bit(RMB) and make the flash media appear as a fixed disk. I'm going to read up on it more before attempting it on my 64gb Sandisk micro SD, but it could be a solution if you are going to leave the same card in your surface forever. (or it could totally hose your micro SD)
I called up the local Microsoft store to see about exchanging my 32gb Surface, that I pre-ordered online, for a 64gb. They said it wouldn't be an issue and they have 64gb models in stock.
EDIT:
There may also be a filter driver that can be installed. The filter driver ignores the RMB, so the micro SD would appear as a fixed disk and no changes would be made to the drive.
Read more:
Filter Drivers – Removable Media as Fixed Disk in Windows | AgniPulse