Had a Permatrim on mine - on a 17' dory - for years.
Comes on plane sooner & stays on plane at lower throttle opening so quite an improvement in fuel consumption which was the reason for fitting it in the first place.
It's a big aluminium plate bolted onto the cavitation plate so I expect something similar wouldn't be that difficult to make.
AFAIAC it does what it says in the blurb.
But as I said earlier, regardless of power etc there comes a point where the weight & position of the load is just too much for the engine.
A case in point was the 'go-bang' for outboards at an annual regatta I attend. Idea is to set off at full throttle from the start & then, when a flare is set off to turn round & come back at the same throttle setting. One year one boat was loaded with passengers who all stayed at the back of the boat, which unsurprisingly was very bow high & wouldn't plane. At the signal the passengers all distributed themselves properly, boat went on the plane & was first across the finish line. Disqualified for blatant gamesmanship.
I should add that it's all in fun, nearly everybody cheats & the winner is usually one of the displacement hulls who can't get far enough away from the committee boat in the time allowed to avoid detection