Can’t you go NNE from 5, turn left between the two rows of buildings, and then slip right and north between two tightly packed demountables to get to the prominent tree beside the impassable fence?
Might get a bit crowded in the narrow passage if everybody’s doing the same thing to go in both directions.
The mapper should have accentuated the gaps between the demountables to make it clear you could pass between them. No doubt when the courses were set, no one envisaged they would need to include OOB lines where the tradies were working.