Cloudflare tunnels are layer 7, so it’s not unlimited access by any means. This also means that certain things will break btw, for example if your website uses websockets to load information, that isn’t supported.
Next, I’d put the computer that is going to be hosting into an isolated vlan of its own and access via external URL only.
If you’re going to use docker images, make sure to vet that they’re updated often and always spin up the latest.