I would like to plant a vine to grow up a trellis I will install along one side of a 7 ft treehouse platform. It faces North so not much sun with lots of tree canopy as well. Fast growing would be good but also thick coverage and hardiness are a consideration. The side of the platform I will trellis is in the picture, under the rectangular front window. Any advice would be much appreciated.
Since you are in full shade and the vine will be climbing in an area with lots of activity, in good conscience I would only suggest English Ivy. The botanical name of this vine is Hedera helix. I am pasting in a description of this ivy from a University of Illinois website:
English Ivy – Hedera helix
English ivy is a vigorous vine attaching by aerial roots and growing 50+ feet long. It is an evergreen to semi-evergreen depending on where it is grown, and the severity of the winter. In open locations and where it is exposed to more wind, the foliage tends to turn brown. New foliage will regrow in the spring. English ivy benefits from regular pruning in the spring to control growth which can become aggressive at times. The vine is also a good groundcover. It prefers a part to full shade location. More sun and wind exposure results in discoloration of the foliage during the winter. Cultivars to look for include ‘Thorndale’ with glossy, dark green foliage and ‘Wilson’ a small leaved form good for small space gardens. Variegated forms often need extra winter protection for survivability and their hardiness is often questionable.
In my experience I have found this vine to be very resilient plant that will survive some trampling which would be good for your situation.
If you find that you are getting some sun in that area and are interested in trying something different click on the link below and it will take you to a list of vines suggested by the University of Illinois.