Stephane:
Good for you for getting tested. I’ve spent a fair bit of time at the Canmore Nordic Center. Nice facility.
Since you already have a high aerobic base you should definitely include some Z3 and Z4 workouts into your plan. You should greatly reduce if not drop all Z2 training and do your aerobic base work in Z1. You are in the enviable position where your easy days need to be easy so that your hard days can be hard. This will move the pace at LT up and if you keep the volume of Z1 high your AeT may move ups some. That depends on your training history. You can do Z2 training but it should be directed and not just going out for 3 hours in Z2. It can be part of a warm up before more intense training. It can even be part of a tempo type workout where you in moving from high Z2 into Z3 and back again. But too much Z2 will make you too tired to get the most from you intensity. This is when Z2 becomes the “black hole” of training intensities.
To really maximize your performance on the long mountain days you will need to include more running/hiking workouts. The bike is just too dang efficient. But you already know this. If you are performing at the level you want to be at then stay on the bike.
Scott