Next year I might find myself needing a lightweight touring/camping shelter, suitable for overnight stops at camspites and at the roadside. One option is a single-hoop bivvy tent (example) but many of these aren't much lighter than my hiking tent, and they're rather expensive. A hoopless bivvy bag seems more like emergency kit to me (with the exception of the Salewa which allows the hood to be lifted with a cord to a branch, fence, or bike). My choice is rather restricted by my height -I'm too tall for many of them. We can a assume a decent weather forecast before setting out for a few days, so some need for rain-proofing (and face cover) but not planning to be out in a storm.
As an alternative I wondered about getting a tarp, and using the bike itself (held up with guy ropes and possibly a kickstand) to lift the head end. This would have the advantage of no poles to carry, making packing very easy. Has this been done before? Are there any plans in existence? I've got reasonable DIY/craft skills and equipment but not really for working on fabric beyond minor modifications.