Me being a twig too, had a hard time doing burnouts also. Skidded the front wheel a bunch of times like a tard too. but then i got the fear of some flip over instantly if I clutch dump it standing there nightmare outa my head and tried it. Slipping the clutch out trying to feel it break loose is harder to do for smaller riders and all that does is preloads the suspension a bit, so if you dont have the weight or the height to get leverage on the front tire and hold it its hard to do. The preload and the geometry built into the rear suspension is fighting you, wanting to plant the rear tire, and unload the front.
Reving it a bit, and snapping the clutch out shocks the tire and doesnt give the suspension enough time to load up and try to plate itself into the ground on the back tire. Keep your ass off the seat, nuts on the tank and hang over the windscreen to plant the front tire, snap the clutch and commit to it.
Same thing i found out doing rolling burnouts. I thought for sure the first time I tried it I would grip and loop over instantly… nope, my ass is too light even sitting on the bike and didnt have to use the front brake either! lol cold tire that is, warm tire its a little grippier.