Pervert indeed.
Those all steel early golf bumpers are quite pricey now as people know what they have and its trendy to have them, I would say try scrap yards but most have already been snapped up.
Sliding rear window is possible, one of those american style ones with a centre panel that slides, May have to make up the channel that the glass sits in and the glass will be just toughened and cut to template, a decent glass shop can do that for you.
Sticky back plastic wood style sides, now that is station wagen, A bit national lampons vacation.