Hi everyone and thanks for your kind answers.
I checked a couple of BBB hosted providers but they are quite expensive for our use case. We're starting with one or two events a month, and their monthly subscription seems like too much for just that. I think we'll choose the path of a VPS with a script to install everything and destroy the VM afterwards. I'll take a look at your suggested VPS. I even found a script in the list archives to use as a base.
By the way, I found this french provider:
https://ensemble-bbb.scaleway.com/. They're offering free BBB conference rooms until the end of July. I proposed to my group to make a couple of tests of the software features with them before starting the events. They seem to have kind of a BBB template with Ubuntu to auto install everything but have not tested it. And I didn't check the _javascript_ trap issue either.
Some of the people I've been testing with Jitsi Meet and BBB have poor internet connections. There are some teachers who work in rural areas and I noticed that Jitsi Meet requires more bandwidth than BBB. Not sure why, maybe is for the V8/V9 codec thing. BBB had no sound issues while a conversation with Jitsi was impossible sometimes.
The whole university can't even spare a VM even for a limited time on one
of their servers?
The university can, but we're doing the events with the university library. I'm not sure what's the problem but I think it's internal bureaucracy. The IT and the library are like different departments, so they have to go through a lot of trouble to get the resources. We're planning on presenting a project to them, but that may take a whole year before getting somewhere.
Thanks again for your comments and your time.