Load towing load

Hello Community, I have a 535d Touring xDrive (EZ 07/2016) with an electr. swivelling trailer coupling installed by the factory. The maximum towing load is 2000 kg (braked). I would like to buy a heavier trailer now and came across the topic of loading. Unfortunately, the customer service from BMW did not reply to my request. Does anyone have any experience with a load up here? I already have the references to Auto Technik Bihler and S.K. Handels here in the forum. GmbH found. S.K. says that they have no possibility for my car, Bihler says very probably possible, on 2300 kg (incl. support load up to 8% incline), about 600€ cost. However, as with any deviation to the series, BMW could reject the manufacturer’s warranty (I have a BMW Premium Selection warranty that runs for just under 3 years). Are there any other options? What is “legally” actually a burden) Thank you!