I have computers to deploy and want to apply changes to the default user policy on these PCs automatically. What's the best way to do this?

Our current procedure is:

1. Create the computer account in an OU called "Deployment" on our server
2. Unbox the PC
3. Login as the user who will be receiving the PC
4. Change settings (pre-configure outlook, authorize Office, etc.) move computer account to correct OU
5. Place the PC on the users desk.

I would like to make as many of the changes in step #4 with Group Policies applied to the Deployment OU if possible since they're largely repeated for every computer. There are a dozen policies created and the computer ones apply correctly but the user policies do not.

I understand this is because the end user is not in our "Deployment" OU. I don't want to apply these settings to the user at their current station just the new PC I'm working on.

I believe I have the desired effect with Group Policy Loopback Replace enabled on policies that need user policies changed but this just feels wrong/inefficient/complicated to maintain.

Am I doing this correctly? Is Group Policy Loopback the only way to change user accounts on one computer? What do you do to setup a user on a new PC?