I have grown a rambler up a mid-sized tree
with reasonable success (it snakes along the branches, tied down, in excess of 20 feet above ground). But I think there are various factors to take into account:
the depth and extent of foliage on the 'parent tree
' ie so that there is enough light for the rambler to get established.
feeding and watering: there should be enough nourishment to keep both of them happy.
needs to be robust enough to support the rambler and not get smothered by it.
they should complement each other, both in terms of colouring (flowers
and foliage) and 'architecture (ie they shouldnt look ridiculous!)