stardust,
That is essentially correct, as the wing lift at stall is a relative constant amount of force, so the load factor drops as the aircraft's mass increases.
Of course, the ultimate load factor is not a fixed quantity, becasue it changes based on the distribution of loads. If the fuel is in a belly tank, the wing stresses on the roots are the same, even at the lower load factor due to a higher mass (the wing lift is the same at stall, so the loads on the fuselage joint are the same). If the fuel is in the wings, then the wing root loads are truly lower at stall.
For fixed masses distributed around the fuselage, such as the engine, your rule of thumb is quite right (except that generally these items are strengthened to withstand crash loads that are much higher than flight loads).