Alternate app icons and AppStore test treatments

We want to provide an alternate app icon in our bundle specifically for testing with an App Store test treatment (A/B test).

What I'm unclear about is whether we then need to enable users to choose from the available app icons, since there are now multiple. I have seen reports of apps being rejected because they didn't offer this feature when multiple alternate icon sets were bundled. We do NOT want to allow users to select an app icon.

Also, is it permissible to have a different icon for the App Store than what is used for the device app-launcher? I believe the guidance here is that all sizes of the icon should have the same content (just resized), but our marketing people want to test a different icon for the app-store specifically.

Is there guidance on this somewhere that I haven't found?