Thanks!
I think I miiight have found an exact match: https://www.aliexpress.com/item/1005005073296395.html Not sure what a waterproof USB port is used for but it should do the trick. I'll buy a few other connectors of similar size to hedge my bets and do as you say if this one doesn't quite fit.
Looks like I'll be starting a new plastic compartment container...
I have a form like this I do regularly for work. I actually fax the form, I don't even send it electronically. But I like to fill it electronically so I have my records on the computer. Because it is 2023. I had to use my home computer (linux) to generate a copy of the form, then use a floss editor I managed to get working on windows work computer to annotate on top of the form fields. For some reason it's really hard to get the annotations to line up with the form fields. So sometimes I have to correct it by hand after printing to clarify.
It is a zero security form, there is no need to have all this rigamarole. The form is freely available on the internet and anyone with a fucking fax machine could fill it in and send it on behalf of anyone else. Fax machine is the biggest hurdle; who the hell has one of those.