Can I use mirroring to make a copy of my Database?
The main problem with mirroring is that if you have a network outage or get disconnected mirroring will stop. So across networks it is better to use log shipping. 

Additionally it sounds like you have a vldb or poor disk i.o based on your time listed in your question which is why you might prefer log shipping for the migration as you would only need to restore the last log to bring up the new database. This is ideal for minimizing downtime.

This blog, while old, highlights some points i explained