I have done burning of bramble patches as slash and burn, which is maybe a little bit different. I used a machete to cut away the brambles, and piled them up. After letting them dry out in the sun for a few days (fingers crossed no rain), the piles were burned, which they did readily, and I was able to rake the still smoldering piles out across the ground, spreading the embers and ash around in a layer to simulate a more “complete” burn. Lots of new black-cap raspberry shoots emerged out of the ground over the following weeks (as well as lots of Phytolacca americana – roots?), but I was actually going for the creation of a meadow so I cut them down again later. Nonetheless this could be a practical way to get the effects you want.
I’ve also done some burning of grasslands but for that I would suggest having several people around to help out because things can get out of hand REALLY FAST.