How do you drive backwards with the brake?

Hello, I want to increase my 1st woWa this year, and have one or the other question for driving with such a part. At the moment I am most concerned with the one after the back riding with speed brake. How does this – above all uphill – without the downhill moving trailer braking itself, and thus all forwarding is impossible? You can not open the brake on a slope anymore, because the WoWa keeps coming after me. I like such a joke. I don’t think it would be very funny to imagine it on unpaved ground. Greetings, Oliver