I use an REI backpacker's poncho. It's longer in the back (enough to drag on the ground, so it folds up with snaps so you can use it without a pack). Inexpensive, tough, and big enough to cover pack and me to (I think) mid-calf. Not blaze orange, though, and I don't recall if that was an option. Some reflective tape might work, but a blaze orange "blob" would certainly stand out!
REI member since 1978
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