Alot of us also use a "whiptail" connector
out of the back of the B2. This means you do not have to go in to the back again if you need to move the unit.
Unfortunately there is no room at the back of the B2 to extend the Raspberry Pi's Ethernet Port to the back of the B2, or I am sure Martin would have done it.
HOWEVER a Wired Ethernet connection can also be made using one of the B2's USB ports and an USB Ethernet dongle. This solutions requires you to load the correct Ethernet drivers from the Front menu control system.
Fred