I haven't rebooted the tab for almost 72h, I travelled with it, it also had long periods of deep sleep, and until now, no network loss. Seems like the last RIL might have solved it. I can still see small sections of red in battery history indicating that for a few seconds/minutes maybe the tab lost network but then regained it (I didn't see this in my phone's battery history, same places travelled, same network provider, but I'm hoping it's just a glitch). I'll be keeping my eye on it.
It's also sleeping wonderfully compared to the previous builds. It used to stay at the lowest frequency most of the time, now deep sleep is dominating the cpu stats, and it reflects that in battery life.
Great piece of work and display of patience and perseverence, pershoot.