Hello Randy,
two notes :
a) the loop command should have more then one option may be loop network is the right one for your scenario
b) When you have a POS interface looped it is usually to perform OSI Layer1 tests with specialized instrument connected in place of the router on the other side.
But I see you would like to perform tests at OSI layer 3 with IP traffic generators.
In order to make this setup to work you need PBR policy based routing applied inbound on router B POS interface for destination 192.168.2.2 otherwise is traffic is looped on the POS and wil expire over it.
When T BERD B sends traffic to 192.168.2.2 the router B will receive it on a different interface and will route it to the POS using the static route.
When traffic comes back from the looped POS the PBR will send the traffic to T BERD C, but for this to work RB interface to T BERD C should not be in 192.168.2.0 network.
Well for me this setup cannot work this way.
The simplest test you can do after the loop is operational is to ping 192.168.4.2 via RB.
Also the network masks for your static routes should be /24 not /8
Hope to help
Giuseppe