I have successfully and rather easily deployed the XPSingle environment found here: https://github.com/Sitecore/Sitecore-Azure-Quickstart-Templates/tree/master/Sitecore%209.0.2/XPSingle. Pretty pleased with it overall!
However, now I want to modify my ARM template to separate the CD server into a separate App Service - while leaving CM, Reporting, Processing on the first.
Is it as simple as modifying the WDP for Single to remove the CD role, and then adding the appropriate one for CD - and adding the correct resources to the azuredeploy.json?