Here's an idea for a roughly 9 km LRT route for Gatineau that could be extended westward along the 148 corridor and incorporate the future conversion of the Rapibus to LRT. I think this has more TOD potential than the river route, and the investment would be useable by more residents in the short and long term.
Excuse the size of the following diagrams as I wanted to have them all at the same scale. 60m platforms would probably be sufficient for a long time, using a train similar to the expanded version of Ottawa's Citadis
I imagine this sort of integration with the Confederation Line at Lyon, and either using the Portage Bridge or just excavating a tunnel under the river:
Continuing in a cut-and-cover along Maisonneuve:
And then westward either along the highway or by implementing some road diets:
It would service Galleries de Hull and The St-Joseph main street:
It would make the hospital more accessible, and imagine being able to ski Gatineau Park coming off the LRT
It would terminate BRT plaza near the cinemas in the Plateau until a future phase to extend it all the way to Old Aylmer: