Personally im a big fan of cramped spaces when it comes to gmod, and I also love maps like this. I feel like a ventilation system could be perfect. ive already suggested this to the creator before but im simply posting this for the memes. the vent cover could be broken or taken off and you could climb in, being able to traverse to different corners of the map (if all vents are connected to eachother, of course.) this could be hard to do consider the map's layout but if done right i think it will be amazing.