No URL based firewall, what to do?

Hello,

If you block http & https and force through squid, some RMM tools seem to suggest leaving 443 open, and they give a bunch of URLs to whitelist but of course we cannot whitelist by URL https except for things proxied through squid… so we block port 443 and force through squid but the RMM agent does not allow the use of a http proxy so it gets blocked.

What can one do in this situation? Aside from tell the RMM creator that their agent sucks for not allowing the setting of a http proxy.