Any short rib will not do well with heavier engines or heavier people for that matter. Unfortunately, most of us have size or weight limitations. There is a point of being reasonable regardless of what the manufacturer says. My inflatable
is rated at "15HP Max and 10HP is Recommended". The 10HP is more than adequate for planing, I have a 9.8 4-stroke. I'm sure a 15 HP will pull the stern down.
When I put my 9.8 4-stroke on my 9' dink the rear really squats badly and the boat is rated for 10HP. But that was 20 years ago with 10HP 2 stroke
which probably would also have been too heavy.
Many manufacturers are overseas where 2-strokes are still legal
. The manufacturers get to play dumb here so they can impress you with a larger HP engine
. If you have a 9' dink, I would think that a 6 or 7 HP would do you well.
The 9' dink came with my used 36 Mainship. After using it for almost a year, I would not recommend anything under 10'. Unfortunately, if 9' is all you can carry, you are stuck with it.
Towing is always an option but not always a good one. I have towed before but rarely with the engine on it, for obvious reasons.