This will work in any part of the game. Go into your control settings and bind "toggle developer console" to a key. I bound mine to ` but it doesn't matter which as long as it doesn't conflict.

Next, in the map, press the key you bound it to, and


type: sv_cheats 1
and press enter
then you can type: noclip
and press enter this will let you fly around the map without collision, type it again to turn it off. If you get stuck, turn it on again and reposition yourself before turning it back off
type: god
and press enter, this willl make you unkillable if you're having trouble navigating around the kill planes of the map, type it again to to turn it off.
This can be used to get back to where you last left off. Both of you will have to type noclip or god as it is individual to each player, the host will have to be the one to type sv_cheats 1. Im surprised nobody answered this already, hopefully it is still of use.

atlas is always the host btw

thx guys!