I have seen products advertised that are kind of like a swiffer sort of wand thing that either already has a microfiber pad on them or you can clip a rag. Basically just makes wiping steeply slanted windshields and stuff like that down. Could work for the rear window maybe, but it's still tough to get back there even with a tool. If you could get someone to hold the top partially open that might be a slightly easier way to vacuum out the little carpet tray, but it pretty much ***** no matter what you do. Just not much room between the roof and the top of the rear waterfall panel.