Have you actually lake tested it with the 17" motor yet? I strongly recommend that you do before making any decisions, and here is why...
I recently bought a Tracker 16 with a 15" transom, and it came with a 17" Johnson 30. I thought it was too long, so I put a 1" block on the transom and clamped it on. It ventilated badly during turns and I had to accelerate gently or it would blow out. You can see the block of wood if you look at the bottom left side:
I pulled the block and ran it again. It ran much better, didn't blow out at all. In this video, I tilted it up one hole, and it was a bit light in the nose, but it was perfect once I had a trolling motor and battery up there. But the 17" motor turned out to be perfect for my 15" transom. So definitely water test before making any decisions: