design advice for GTM config for vpn devices

I'm looking for guidance for setting up my vpn devices. I have two datacenters with a single vpn device in each datacenter. There is also a gtm in each. I want the local gtm to monitor status for the device normally. If the local gtm goes down, I would like for the remote gtm to monitor the vpn device and send traffic to it if it is up. I have upgraded the gtms to version 11.2 so that I can make use of proberpools to lock the monitors to the gtms and not allow the local LTM pairs to do the monitoring. So my question is, how should I set up the proberpools - local gtm only or both? Should the traffic pool(s) be setup as one pool with two members or two pools with one member each? I understand that this isn't extremely high level stuff, but I'm trying to make sure that I minimize the cross-datacenter traffic (only talking across when I have to).