How about changing the current practice of logging P1 US from the right hand seat?
P1 time should be just that. P1 in the left seat.
For the ATPL issue you need eg 250 hours P1. Not P1 US or however it's dressed up now.
This is different to trainee captains sitting in the left seat with training/check captains occupying the right seat.
I think a mind set change would need to happen too. After getting the CPL/IR (not fATPL....) pilots should view their subsequent hours as "working" not "hour building". I realise that in the end it's the same thing but the attitude would be different. Working implies a job with remuneration.