With these 2h rides in the first phase of the plan I’d probably suggest to go in sort of “low”. Perfect would be in the morning with only an omlette or so as breakfast. And than a banana half way through.
For traditional base on the road with longer sessions I aim for 40-50g/h. Often I would start fasted or with a protein breakfast. However, I would start eating after 60-90min at the aforementioned rate. One has also to consider that base rides can come in different flavours. 5h around AeT is a different beast than at the lower end of the relevant intensity spectrum.
Did quite a lot of no fulling workouts for two winters. Ditched this again and saw overall progress again. I mean it was great coming back home with a huge calorie deficit but I find it more sustainable for progress when not too much underfuling occurs. And one does not really blunt the adaptions when feeding later in a ride.