Doing the Old Ghost Road the ‘wrong’ way

I'm bikepacking the South Island of New Zealand and found myself in Karamea after completing the Heaphy track. Considering how close the northern trailhead of the Old Ghost Road was near Seddonville, Ive decided to tackle that next. On their website it says riding North to South is not recommended. Has anyone here completed the track starting in Seddonville and heading to Lyell? How much harder is it? Thanks!