Here's a step-by-step description of the full workaround, which will enable you to host a private game even during the times at which the master server list crash is occurring; do not select Internet from the Source box at any point during this process:
The host must do the following: open Multiplayer, cancel the login, select LAN* from the Source dropdown box, and then login. Do not select Internet from the Source box. Now that you're logged in to the master server, click on NEW SERVER, then select LAN from the Server Type dropdown box. Check the port number, then hit START.
All clients must then do the following: open Multiplayer, cancel the login, select LAN from the Source dropdown box, and then login. Do not select Internet from the Source box, as this will cause the crash if the bug is occurring at the time. Now that you're logged in to the master server, click on Connect by IP, then enter the host's external IP address and port in the following format, without the brackets: [address]:[port]. For example, if the host's external IP address is 18.104.22.168, and if he is using the default port of 10308, then you will enter the following: 22.214.171.124:10308
If the host is correctly configured for hosting in general--that is, if you're able to join him normally using the Internet source during the times when the server list is working properly--then you should be able to connect. If you can't, try restarting the program; a single restart of DCS has done the trick so far in each case, for everyone who has attempted to join my server using this workaround.
* This is mislabelled; it should read "direct connect" instead of "LAN." So, it works for remote connections, not just on local area network. E.g. it'll allow someone from Britain to join a host in Germany, and so on, rather than requiring the two to be in the same building.