Does anyone know if it possible to arrive into Azerbaijan by (overnight) train from Georgia with an eVisa? The website for the ASAN visa doesn't mention an arrival restriction, but I have read that there is no one at the border at night to admit you to the country...
Yes, it is. I have traveled to Azerbaijan last month and met lots of people on my way, who have arrived from Georgia by bus or night train, having eVisa.
Border checks are total, as almost anywhere except within the Schengen Area.
As such, you will be checked and yes, you can use your e-visa.