The mobile outpost from afar, complete with three important-looking work stations.
A closer look. The transporter is visible here. I envision this mobile outpost as being an accessory to the A209 Mobile Command Fortress with this transporter pad functioning as a receiving pad for the A209's own transporter system. There's no way that the Echo 1 is carrying enough hardware for a full transporter array, so it instead strengthens and, if necessary, reroutes transporter signals from the A209 across great distances. This also allows crews to rotate to and from the A209 without having to utilize valuable resources on the Echo 1 while off-duty. You could theoretically transport an entire army via this receiving pad without having to actually drive them to their destination.
To convert the outpost into truck mode, begin by collapsing the satellite array and facing it toward the wall.
The second floor balcony then rotates clockwise.
...and rotates clockwise some more.
The roof is then lowered while nudging the transporter array as far away from the protruding ground floor work station as possible (the entire balcony is mounted on a black swivel connector).
A four person crew can fit in the cab module.