GWT+Eclipse without GWT_CONTAINER

GWT+Eclipse without GWT_CONTAINER

The situation
I'm using GWT with Eclipse and Google Plugin for Eclipse (GPE). Gradle is
the build tool and the Eclipse classpath is generated by Gradle. As I have
no "com.google.gwt.eclipse.core.GWT_CONTAINER" on my classpath, GPE always
shows the error "The project 'Test' does not have any GWT SDKs on its
build path" and the Console sometimes prints "GWT SDK not installed.".
Annother effect is that Eclipse doesn't let me GWT-compile the project
(but running dev mode works fine). But that one is ok for me, as I compile
using Gradle.
Things I'm aware of
I know that I can exclude all GWT depedencies from the Eclipse classpath
and add the container through Gradle (I did that for other projects). But
as I can't enforce the GWT version provided by Eclipse (I can only specify
the SDK's name in the classpath by adding the suffix "/" to the
conatiner), I think thats an ugly solution. Another point is that the GPE
update site only lists the latest GWT version available. There's no way to
automatically install an older version (yes you can provide one
externally).
When using GPE together with Maven and m2e it simply works: GPE links no
real SDK for Maven projects but there's a link to the "com.google.gwt"
group in the local Maven repository. But that's magic I can't use because:
Gradle's local repository format is different to Maven's
This logic is implemented in the plugin "com.google.gdt.eclipse.maven" and
I can't use that without adding a pom.xml to the project
The questions
Is there a possibility to deactivate this nasty error without loosing
other GPE features?
Is it possible to do something similar to what GPE+m2e does without
creating my own Eclipse plugin?
Am I right that excluding the jars and adding the container is the only
viable solution by now?