ok, having cogitated a bit on the original question, how about a decent PTZ? I know you mentioned, "no PTZ", but
maybe you only meant to say you don't need to move it once set up? A decent PTZ with 45x zoom should be able to
give you >100PPF at 500m (per IPVM calculator for 2MP cam @150mm focal length.) You'd have to mount that sucker to
something real solid tho... Anyways, this could do it, perhaps:
US $688.75 5% OFF|Security CCTV IP Camera 2MP 45x Starlight IR PTZ Network Camera SD6CE245U HNI for Dahua Without Logo -in Surveillance Cameras from Security & Protection on Aliexpress.com | Alibaba Group
other options:
https://www.dahuasecurity.com/search/products?keyword=45x
and i still don't understand where the 1.1km came from when the OP was regarding ~400M...