Hi, i had the same problem with my Zodiac Pro 7 and a 40HP Mariner.
I run the engine with a 13" pitch prop.
When started, the boat was pretty fast idle. When accelerating the end was
pulled into the water and the front raising to sky. After over 3000rpm it was beginning to planning.
I tried 15"pitch prop and 12" prob. Then i fixed hydrofoils for 16,50€.
It is totally different. The boat is beginning to plane from 2300rpm on and
running lightly. I have a steering console in the middle and a double bank
in the back.