Child seat: how to protect my child's face from rain and wind? I edited this question more than any of my questions before, please feel free to view old versions. The overhaul of the question was approved in principle by a moderator. I did also add an answer with one other solution I thought about, but that is still only a concept and I would love some opinions.
Objective
I am looking for a way to protect my child's face from rain and wind while in a child bike seat. I'm not a scientist but she gets cold easily and my parental instinct is that even partial cover/protection of the face would reduce wind-chill noticeably. It's for getting my child to school, just a steady 15-20 minute ride but we live in England.
There seem to be no purpose-made products readily available on the market (except from an amazon seller who doesn't look trustworthy). And product recommendation is, controversially to say the least, not allowed on stack exchange (but I'd love a link if they exist).
First thing I could think of
Convert a Rain cover from a &quot;rucksack&quot; child carrier to attach it to a bike seat

Has anyone ever done this? I would like to minimize damage/modification to either product. How can I attach one to another? Do I need to 3d print some fittings?
Factors I need to balance
Usability, breathability, crashworthiness, constructability, wind resistance (from being blown away or into child's face), entanglement ...
Options discarded
Naturally one way would be to use a trailer but I am very reluctant to do this:

I don't really have room to store it,
there are chicanes on our route to deter mopeds/motorcycles etc.

My child is too big for a Thule RideAlong Mini Windscreen - it's a product intended for a seat for smaller children, sat between the rider's arms.
Any other alternative ideas will be welcome.
Hamax certainly make a dedicated cover, though when I had a Hamax seat I used a cover from another brand (Raleigh I think). Both keep the child's face uncovered.
My worry with that design is that with plastic sheet in front of the face you really need a sufficiently sturdy support to hold it clear of the mouth and nose, even if the child falls asleep and the wind is at its worst (despite the plastic being fairly stiff). But the support mustn't be a hazard in its own right, for the rider or child, even in a crash. I'm not saying it's impossible, just that it's more challenging than you think to make it safe. You'd probably have to destroy the rucksack to obtain parts, unless you had something very similar to dismantle