OP, you should consider selling. These transmissions are ticking time bombs. I towed a jet ski and it started slipping after 10 miles. Not to mention the pink milkshake that happens all the time. IMO this transmission cannot handle the power and weight of this vehicle.
How involved is flushing a transmission?
To do a true flush you need to take it to a shop and have them hook it up to a machine. I had mine done at the beginning of the year and I took it to the dealer. Jiffy Lube will do it as well, but their price was the same as the dealer so I decided to take mine to the dealer.
How much did that cost you, if you don't mind my asking?