Ok, somewhat complicated.
Does the zipper have two sliders, which can "meet" at the collar? One down from the hood and one up from the bag? In that case, you might be able to use a string for opening the bag, it is well possible, that the hood keeps the zipper line straight when you pull down. On my bag, the zipper line will bend at the collar and not open at all.
I suppose, you can get into and out of the bag alone, if you don't use the inside sleeves. So you can test everything without getting trapped, simply pretend, you can't use your hands. And you can start wearing the zipper in front. Perhaps you should consider making eye-holes into the hood.
Does the zipper have two sliders, which can "meet" at the collar? One down from the hood and one up from the bag? In that case, you might be able to use a string for opening the bag, it is well possible, that the hood keeps the zipper line straight when you pull down. On my bag, the zipper line will bend at the collar and not open at all.
I suppose, you can get into and out of the bag alone, if you don't use the inside sleeves. So you can test everything without getting trapped, simply pretend, you can't use your hands. And you can start wearing the zipper in front. Perhaps you should consider making eye-holes into the hood.
