Setup looks good. If I understand you have AP lighting to the rooms with vertical orientation. So on the wall with leds down and the front of AP looking on rooms door.
What I often change is Distance between APs, this can help sometimes.
Yes IMC with WSM is available as trial for 60 days on the hpe.com website. And can help you to better analyze the problem.
Did you try channel change? How looks the wireless situation onsite? How much WIFIs are around you? I am thinking about interference. From my experience this can cause lot of headaches. Especially if the hotel is inside the city. In "my hotel" there are about 120 WIFIs network all around.
Firedoors can be very big problem and also Bathrooms and WCs. Everything is in play. Did you compare the situation if the room door is opened? Just idea.
90 rooms can be problem. Last resort is MSM517 as I wrote. But it requires one ethernet in the room.
Totally dummy idea is to take a look around if you are not in visible distance from some bank or similar security-oriented building. There are some technics (also from HP called as RF Manager) which can significantly limit WIFI. But as I said, this is totally dummy.