Definitely not daft. I'd never leave Alfie overnight - a) he's a single rabbit anyway, so would be too lonely and b) a lot can change in 24 hours. Considering how quickly rabbits can go downhill, I'd not be prepared to leave mine longer than 9 hours ish. I think the longest we've ever been away and left him is probably 6 or 7 hours, but that's long enough for me to be comfortable.
If yours developed stasis/bloat/any other ailments just one hour after you left, that'd be another 23 hours before anyone spotted it and by then it may well be too late. Even if they were still alive, they'd have been in pain and may be beyond help because of how long they were left. Plus, I don't see how you can feed them whilst not letting them gorge on pellets all at once - how can you spread it out? Or am I just being really daft..
So in answer to your questions, 9 hours would be my limit.