A few thoughts:
1. If weight loss is the goal, wouldn’t the OP be better of hiking instead of running to save his ankles? I see a lot of fat mtn bikers with wicked strong legs who crush the descents. Same with swimming. Go to Aquatic Park in SF and see all the fat people crush very cold water swimming. Mechanical advantage on the bike and buoyancy in the water won’t transfer as well as hiking. Walk before you run.
2. Squats in the gondola! I am running up and taking the lifts down this summer to preserve joints and time. But I’m checking my phone while seated on the gondola. Perhaps I need to sneak a rock on and continue the workout.
3. I read a blog post by Gaston or his crew in which they discussed supplementing bike rides for very long days to avoid running wear and tear, This doesn’t apply, imo, to the OP. In time maybe. HE needs weight loss which will be easier weightborn. No sure he needs to try to run though. Just hike until the joints recover.
Edit: Don’t think the mental benefit of training on long rides will transfer unless you are very new to endurance sports. Given your current volume of hiking (pretty good! Remember not to beat yourself up too much emotionally.) you know what hard feels like, the temptation to quit, the temptation to take an extra day off. I think you might just be returning to running too soon for your ankle. If you can handle the hiking, keep doing it until the weight comes down.