Hi,
1) You can use "exportAsString" api call to get the contents in the necessary form and then you can push the data using XHR to your own proxy instance that would set the name as you require (the name is set by the export proxy service):
To install your own proxy service, follow the instructions here:
2) Alternative approach would be to still use exportAsString in combination with magic internal method:
http://jsfiddle.net/7gfcjkpo/
Support Team