what you can do is hang a line with weight on it like a plumb bob, this line from point above cl
Then have weights, the more the better at a certain measured distance
outboard
measure the angel of the line when the weights are there in place either by marking the plumb line where it hits the
deck,
cockpit saloon sole whatever, by trig or just sent the measurement to him, This is how I did inclining tests
you could if you have a sailing
boat suspend something from the boom and swing it out but you need that plumb bob, you can also mount a protractor behind the pivot point and read angle off of it
cheers Stu