This is going to sound like a stupid idea, and yes there would be issues.....
However. Here goes.
In today's computer driven aircraft, it would be possible to "separate" the two sides of the cockpit from each other.
One side flies the aircraft for real.
The other side switches to a simulation/computer game mode.
During long sectors, pilots take turns on the computer game mode flying through random scenarios.
Yes there is no simulation of aircraft movement, but this is a relatively minor loss in airline flying.
Nobody loses their own time to practice.
Long Sectors get less boring.
Pilots get more hands on and experience of the bad stuff which thankfully is less and less common in the real world.
You would have to have a very robust system to get everybody playing together again.
Only certain low workload situations would allow it.
It would be difficult to stop the actual real world pilot from becoming distracted by the more interesting game sitting next to him.