From appedix B 6-112 the mast definitions only state that there must be at least 3 supports. 1 at the roof line and 2 on the wall and capeable of supporting a 270 kg cantelever load. The maximim unguyed length above the roof is 1.5 meters. If the mast can support the side load with less than 4 feet below the roof then I think it is OK but maybe the mast cannot normally support such a load with such a large cantelever above the roof and the 4 foot thing arises from that.
