Multiple WAS nodes on a single machine managed through one deployment manager

We have a single server machine where we need to setup multiple Websphere "environments" for our project - these include the Development Environment, Testing Environment, etc. We'd like to set these up to achieve the maximum possible isolation and segregation of the individual WAS servers that will make up this environment. One of our drivers is to ensure that each of these environments, though on the same machine, can be administered and managed independently without any impact to each other. Also, we'd like to manage all of these environments centrally using one single deployment manager (NDM).

One thought we had on this end was to setup a different WAS node for each environment, and have all the servers for one environment under that node. Based on some reading, we understood that this is feasible using the concept of a WAS "configuration instance". However, the limitation with this seems to be is that one cannot federate these configuration instances to the deployment manager.

Has anyone come up with another means of achieving this, given the limitation that we do have a single physical machine to use for multiple environments?

Any help on this would be most appreciated.

What I feel, there is no need to recreate multiple WAS instances, also there is no need to install Network Deployment Manager. Your objective can be achieved by installing base application server. In case, you want clusters of application servers to support different environments, then you certainly need to install Network Deployment, as base version does not support clustering.
Create separate application servers, or clusters for separate environements (say, dev_server, test_server etc.), create separate virtual hosts to for your environments (say, dev_vhost, test_vhost etc.). This way you can have different URLs for different environments. In case, you have to deploy same application to diffrent app servers/clusters, all you need to do is to change the context root inside ear file.

You should be able to create as many individual servers as needed under one node. You can scope resources to each server and you can create different virtual hosts as needed.