You're supposed to make a hole in the back slightly to on side to route the fuel lines through.
This is identical to what is called for with the Modellbrau and even the Kingcat.
Assuming that you are using a gas or nitro engine, there should be no issues with pressure.
You have to make sure there is no air in the lines.
With my now defunct Falcon I put a "T" between the motor and the tank all the way at the rear and filled from there. That made sure the lines were full of fuel before startup.
The Turbine conversions use a pump for fuel.