At Heathrow, BA 747s are catered through doors 1R, 2R and 4L. Catering via 4L involves a very careful approach along the trailing edge of the wing, then a last-minute turn to get perpendicular to the fuselage. Would be interesting to see that modelled in GSX. For info, the same truck does door 1R and 4L; the truck that does door 2R does the Upper deck as well via the internal lift.
For further info, 777s are catered via 1R, 2R and 4R, as are 787s. A380s are catered via 2R lower and upper, then 4L lower and upper.