Ultra shadow prop setup

[4czn10]

Took the boat out today. Had 6 people and about 35 gallons of fuel on one side and 7 on the other. Not ideal conditions,I know. First run everyone was sitting in the back and couldn't get it on plane. Moved 4 to the bow and around 4000 rpm, some s turns it got on plane with the tabs down. Limiter is 6000 rpm sand hit that easily. So I'm concerned that I can't get on plane yet I don't have enough prop for wot.

Here are the specs:
Merc 525 whipple
Imco sc with -1 shortie and 2inch spacer (high x) 1:36 gears
P5x 25 pitch

Temp was around 45 and 900 ft elevation

Thoughts?

 

[Singleton]

PM Shippingguy (Mike). He has a ton of experience with the 27 shadow.