I've not done any, but I reckon I'd be looking at about 8 hours+ at least to start with. I quite enjoy riding in the dark on the quieter roads. The biggest issue for me is time away from the home. SWMBO works also, and someone needs to get home to the dogs which gives me 6 hours max, so I'd have to flex the ICAM rules a bit and have lunch at home...
No stretching of the rules I'm afraid. Rules is rules as they say. However, it's not that you have to tell us you stopped at home. But on your conscience be it.
If we stretch the rules for one, then others would want rules stretching too. So rules is rules as they have been since the challenge started 10 years ago.