Lets be honest, the reason people want to board early is to be able to get the luggage in the overhead or sit down and relax.
Flying AA domestic trains you in this discipline.

The issue is addressed by AA by calling the fasttrack in order and does work pretty well.
They are also very religious about said "charlatans" queue jumping and throw them unceremoniously out of the queue.

Maybe unpalatable to some but does solve the problem