i've been down in a hole by myself before... the most important thing for me was the ability to unstrap my board while upside down and/or covered in snow. that and not hitting my head and losing consciousness.
also worth mentioning vents. out here all the mountains are volcanoes and i have come over a roller or berm and been swallowed up by a venting hole that went straight down to rock - sharp volcanic rock - not fun! luckily it was only about 5-6 feet deep. core shot for sure tho