If my reading comprehension is on target you are saying keeping the relative proportion of your training intact but increase the overall training load by about 15% vs what you have done in previous seasons.
Given that you have been carrying a relatively conservative training load it doesn’t seem unreasonable to target a 15% training load increase so long as you maintain the same relative mix that has brought you success in the recent past. In other words, not JUST extra zone 2 training load…if you were doing 3x10 threshold interval workouts now you’re doing 3x11.5…not necessarily that specific but I mean +15% VO2max, +15% threshold, +15% endurance, etc.