There is the possibility that that will work but it more than likely won't, and for one reason: Drivers. Most RAID arrays will need drivers so if you clone windows to the external then boot from that, install the RAID drivers, and clone it over to your RAID array, it should work.
If it doesn't you will need to boot with the windows disk and use startup recovery to load the RAID drivers and repair the bootloader. Just make sure that you can boot from the external before setting up the RAID array or anything.
I have just set up a RAID array on my PC in my sig and I had to load drivers during windows installation or it couldn't see the raid drive, then when the bootloader broke I had to load the drivers from the windows disk to repair the bootloader.
So, yes, you should be able to do it, but you will need to clone the drive twice and then use startup repair if the RAID array needs drivers. That said, some RAID arrays will run on windows' included drivers, but most won't.