You could increase the preferred duration of your rides or at least your long endurance ride. If you select the block on your calendar (base 1 in this image) it will give you the chance to change ride durations.
In this view you can select ride duration for any of your weekly workouts and in changing it, you will change it for future instances within this single block.
You can select up to 5 hours and the plan will ramp you up towards filling that time.
You can also set this duration in the initial plan build which should carry it through all blocks.