Just tarted up our park/sprint mapping for this stretch. Envisage a bike/foot combo would use the boring/interesting bits best. Stretch Moonshine to Totara Park done, its even better.
I've been thinking about an o-marathon down the river, orienteering stages at any or all of Harcourt, Trentham, St Pats, the Retreat map, Fraser/Avalon, Melling, Hikoikoi (and no doubt a few other potential stops on the way that I've forgotten), running from one to the next (with maybe the odd control to direct people to safer crossings, or to keep them awake!). Probably only for elites and other endurance junkies, although I suppose shorter versions could start at various maps along the way (like I think the Turkey Trot used to?) or teams of 2(or more?) could swap at any of the transitions, with the 'resting' team member shuttling a car down to their next chosen swap. Probably need an army of volunteers for it to happen! I guess the main difference is a run/bike event would require the orienteering stages to start and finish at the same spot, a run only event could be a bit more flexible.