Yes, it's feasible to add a custom namespace.
1. Open up CRX Explorer by going to http://localhost:4502/crx/explorer/index.jsp. If you are not logged in, select Login and enter Admin credentials for the AEM environment:
2. Select Node Type Administration and in the new window, select Namespaces
3. At the bottom of the window, select New
4. Enter a URL (for now, it doesn’t have to be a real URL, for example, http://weretail.com)
5. Enter a prefix, for example mysite
6. Select OK