CAN you do it? Well, yes. But it would not be prudent. The manufacturer's hp rating is based upon the the weight of the engine, the hp of the engine, the weight of the dinghy, it's materials, the strength of the transom, etc.
I have a 15 hp 2 stroke engine on a 10.5 ft rigid (fiberglass bottom and transom) inflateable dinghy and it is at the top of the manufacturer's rating. it's a handful at top speed. Definitely not for an inexperienced driver.