Application Development Software

I'm looking for some recommendations for installing WebCenter Sites (11.1.1.6) on a development server which currently has WebCenter Portal (and Spaces), WebCenter Content (UCM/ECM) and WebTier installed.

For WebCenter Content and WebCenter Portal I followed the standard instructions and have been able to successfully start them in the Enterprise Manager, and login to the provided Spaces application.

Environment
Oracle Linux 6 (64bit)
Oracle XE 11.2.0-1
WebLogic 10.3.6
Oracle (Sun) JDK 1.6.0_23

Installed Products
WebCenter Portal 11.1.1.6
Content 11.1.1.6
WebTier 11.1.1.6
RCU 11.1.1.6

Middleware Home Files
ls /app/Middleware
coherence_3.7
domain-registry.xml
logs
modules
ocm.rsp
oracle_common
Oracle_ECM1
Oracle_WC1
Oracle_WT1
user_projects
utils
wlserver_10.3

Webcenter domain:
/app/Middleware/user_projects/domains/webcenter_domain

WebCenter Sites installation
The instructions (http://docs.oracle.com/cd/E29495_01/index.htm) for "Installing on Oracle WebLogic Application Server" say to run "<wl_home>/wlserver_10.x/common/bin/config.sh" to create a new domain.

However as this machine already has Portal, Spaces and UCM installed under a domain called 'webcenter_domain'. My question is: How can I add WebCenter Sites into the existing webcenter domain, if that is the recommended way?

If it's better to create a new separate domain such as 'sites_domain', then how can both webcenter_domain and sites_domain be run alongside each other? This might be more of a WebLogic configuration question, I'm not sure.

I'm looking for what the best practice recommendation is for running these parts of WebCenter together on the same machine.

The WebCenter Sites install wizard settings I was going to use are below, if this is useful. The part I'm unsure about is astrixed:

_./csInstall_
- Installation Directory: /app/Middleware/Oracle_WCS1
- Development type
- Install mode: custom
- Avisport sample (check)
- FirstSite II Sample site modules: (all)
- Single server
- Sites System Admin account: -
- Sites Application Admin account: -
- Satellite Server account: -
- Sites Shared Files System: /app/Middleware/Oracle_WCS1/Shared
- Host name: webcenterserver
- Port of Application Server: 7001
- Platform Type: Application Server Platform
- Application Server: Weblogic
- Site Application Deployment: 1
Path: /app/Middleware/wlserver_10.3
Application Context root: /cs
- Sites Application Deployment: 2
** Weblogic domain name: sites_domain / webcenter_domain
** Sites application name: CS
** Manual Deployment dir: /app/Middleware/Oracle_WCS1/domains

Any pointers would be much appreciated.
Thanks