Windows Server DC/AD in parallel with UCS DC/AD (transition phase)

We are seriously looking into replacing our Windows Server 2012 DC/AD with that of UCS, however the transition phase is what we need to still hash out.

We would like if we could setup a UCS DC/AD host on the same network as our current Windows Server DC/AD exists. The UCS DC would be using a different domain than the Windows Server DC. The idea being that we can gradually test/set up the UCS host, and eventually start to move network clients from the Windows Server DC/AD to the UCS DC/AD.

Is this feasible? Any tips or tricks?

We do not want to migrate AD from the Windows Server to UCS - we want to build the DC/AD/GroupPolicies/etc … back up from scratch on UCS.