There are a couple of limits you're close to or actually exceeding with that size trailer.
A conventional trailer like a toy hauler or camper requires 10% to 15% of its total weight on the ball for safe towing. For a 9000 pound trailer that's a minimum of 900 pounds and the receiver will support only 920 pounds if you have a WDH. If your tongue weight is up to 15% or 1350 pounds you've massively overloaded the receiver.
A boat trailer only requires 5% to 7% on the ball so a 9000 or even 9200 pound boat-trailer is fine.
You need the HD Tow option for anything greater than 6000 pounds.