Master Clock may be best way. You would want Juvie + Reject RNG for the beginning so you can run past them to safe room, pause and restart act. You won’t need to press switch or go inside through safe room door. It should take about 1:20 minutes, then restarting the whole process again from opening pod, run to safe room, pause and restart. It was nearly 500 CXP on Guest account, so with Boost, that would be 1,000 CXP in 1:20 mins.
I’m still confused since I don’t think double class xp was being counted. 800 CXP is Incon Surge / Clock so Master should be 1,000? But double CXP should be making it 1,600 to 2,000, which I haven’t figured out. Someone with Boost could figure it better, since my main already has maxed classes so I can’t track progress with Boost.
Boost users may be the ones with 1,600 - 2,000 CXP earnings, as double CXP event until Jan 4th might only be for Boost owners.