I've got airborne into a ~200ft cloudbase, but that was with the runway end over the sea, with the liferaft on the other seat, the sea was flat, and water is the same everywhere
I wouldn't have done that over land. I would prefer 500ft+ cloudbase if departing over land and even then no high ground or a built-up area.
No way would I fly if the cloudbase was in/under the terrain en-route. But that raises an interesting question about night flight in a SEP, doesn't it? Some nights are bright, many are not, and some which look bright at 5000ft are pitch black when lower down. This is another can of worms to open up... you can fly at night on a plain PPL (with the NQ), you could easily not see anything useful down below, yet you haven't been taught to navigate fully IFR.
Plenty here to keep pprune going
I am off to France shortly (VFR
)