Not trying to throw a spanner in the works here but if 225/65/17 are available for the same speed rating as the ones you currently have fitted, which I doubt, are you aware they are designed for SUVs? This would change the whole dynamics of the car and I believe not in a good way.
I wonder if anyone close enough to you from the forum had a spare set of 17’s with tyres that they could lend you for a week. To see if the ride does feel different.
If you should go down this route could I suggest 225/50R 17’s, there would not be a massive difference in overall diameter in fairness and you might see a small change in comfort, how much I am not sure. I strongly recommend sticking with XL’s though, low profile tyres need them!
I guess in fairness if the local councils actually sorted the pot holes ur back would cope better anyway.
To other members on here, what size tyres do you have on your 17’s. this info could be helpful for this chap.
hope that helps?