Google maps claims Macadamia Castle to Cassegrain's Winery is 373km but even so my 70D consistently only gets 350km on 100% charge (and that is with another 5psi in the tyres, air conditioning on and gentle driving) so I'd find myself stopping at Coffs Harbour Showground to pick up 50km or more range and avoid the stress. The folks at Coffs are very accommodating.