It looks like Rockwell limits the PV800 to one CompactLogix connection. If you really want to communicate with two controllers, poking around in CCW, it looks like a possible workaround could be to use the SLC/PLC protocol and remap your HMI data in each controller. I don't know if the PanelView will see the processor with the IP configured in the application without additional CIP ports. You would have to test that with the hardware I don't have handy now.
If that would work, in the PLC programming you would use mapping in Logic > Map PLC/SLC messages. In there you might map an INT array to file 7 to be read / written by the PV800 as N7:0 and up. You would probably add a mapping routine to map the INT array values and bits to your other PLC tags.
Modbus TCP might be another workaround, but that can get ugly in Logix5K controllers.