@Yves
That plugin states it supports "Ability to provide configuration files (e.g. settings.xml for maven, XML, groovy, custom files,...) loaded trough the UI which will be copy to the job workspace", and that it works in a way that "It will prevents you to copy various similar configuration files to all your nodes. And the capability to edit those files trough the Jenkins UI !"
This is not a solution for case where alternate settings.xml is already provided in project sources, and each project has its own very project specific alternate settings.xml file.
I think the answer here is for me to finally get JENKINS-4693 fixed - given that we have a way to specify an alternate settings location, I'd rather not also have to parse it out of the goals string. Let me see what I can do with the underlying problem.