I have a surface pro as well...and realized that when setting the display resolution to 1680x1050 it looks as it should...there is about an eighth of an inch of the display that is black on the top...but hardly noticeable.
also, have you tried running any smaller shows with the surface? I'm looking to run about 8 wash lights and 2 moving heads...wondering if I would be ok with the surface pro and an APC Mini?