Ok, with your logic, how much can you then exceed 900 hrs/year.
Can you maybe log 1,800 hrs/year...?
That is, since you only log "part time".
In a few civilized nations, where FAA rules are used, the entire flight is logged.
And it is entered in the proper column of the log book. PIC, SIC etc.
As simple as that.
I used to fly at times with double crew. I have PIC time "while sleeping" too...
xxx
Happy contrails