Dragon's kit 6850 provides an optional part, A7, for the rear wall. The instructions tell you to either use this part or apply 4 small PE parts.
In fact, you should not use part A7. The "Bergepanzer Tiger" did not have the tube when it was delivered new to its unit, before it was converted to a "Bergepanzer". It had only the welded mounts, represented by the PE parts.