Good call to drain and check the oil for debris.
Pickup tube come off?
Debris in pickup
Bearings

Thicker oil may help with pressure, but it's just masking a problem if oil pressure used to be 30 higher.

Curious to hear what the oil and filter look like.

Had this happen to me after a rebuild, had the motor apart multiple times, then found the oil lines were reversed to oil cooler, would show at high rpm and cook the oil, pressure was no existent when I got that hot. Worth a shot to look at, also on boat like that, I would figure there are oil temp gauges, if there are you temp readings should be off motor to motor or at least pre/post rebuild if the lines are wrong.

20-50