I am using ReminderFox as a list of reminders and future tasks.
It is simple, interactive con Thunderbird, works offline and, from my point of view, is "in the spirits" of GTD.
The reference to ReminderFox come into mind as a possible hint to devise a "calendar view" in T-R. Something that can be deployed reminding you the ASAP Next Actions and your list of appointments for the day(s) fully synchronized with the "main" T-R frames.
Hope it helps. For me, as for others, T-R needs a better and self-integrated screen for calendar.