How do I control where the output of a ClickOnce application is built (using Microsoft.Build.BuildEngine) to?

Question

I have a ClickOnce WPF application that I am using Microsoft.Build.BuildEngine to build. Everything appears to be working correctly, but when doing a targeted build to publish the application it is putting the published output to .\bin\Release\app.publish

This is despite setting the properties "PublishURL", "OutDir", "WebProjectOutputDir" - is there another property that I can set to accomplish this?

Is there a way to control where the app.publish directory is created?

projectToBuild.SetProperty("OutDir", workingDirectory);
projectToBuild.SetProperty("WebProjectOutputDir", workingDirectory);
projectToBuild.SetProperty("PublishURL", workingDirectory);
projectToBuild.Build("publish");

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It looks like it always publishes to "OutputPath"\app.publish I've tried the following:

var myOutputPath1 = projectToBuild.GetEvaluatedProperty("OutputPath");
projectToBuild.SetProperty("OutputPath", workingDirectory);
var myOutputPath2 = projectToBuild.GetEvaluatedProperty("OutputPath");

Unfortunately myOutputPath1 and myOutputPath2 are the same, it appears the "OutputPath" is not being updated.