For region monitoring (typically used for the "notification" case) the limit of "fences" is indeed 20...it gets into a bit more detail about "what's a fence" [edit: most of the time you can assume one monitored beacon == one fence]. But for "ranging" meaning "what beacons with this UUID are around me", the system gives you a report of visible beacons every second with no (defined) upper limit.

You can monitor for one region per UUID, meaning that if all of your 1100 beacons share the same proximity UUID, then you should be good.