You can get a thread dump from the Designer using the jstack util.
Run jps, find the process ID for your Designer, then use jstack to dump the threads.
Post both a Gateway and Designer thread dump here, taken while hanging.
Designer logs are a little trickier; look in ~/.ignition/clientlauncher-data/designerlauncher.log. There will be a line starting with "Starting Java with the following parameters:". Copy the long command the comes after that, paste it into a new terminal, run it to launch a new Designer. All the logs will be dumped into the terminal as the Designer runs.