I used to have a Zodiac Yachtline 3.4m rib (open tender rib, no console) with a 25hp Yamaha outboard, which was the max HP allowed. The two suited each other down to the ground, and it was a nippy little rib for its size. Used to pull ringos with it often and skiing too! (though I did have hydrofoils on it to help get on plane quicker).
I would say you need 15hp minimum if you want to comfortably plane with 2 people, especially against a strong wind/tide etc. Though if you can stretch to a 25hp motor then I don't think you will regret it at all, depends what you need! Though that said if you are removing the engine daily, then carrying 52kg is not much fun, trust me! Though it is doable!