If you have too much slash to work with beyond a hugel bed, just pile it up in places where it will benefit other
trees and let it slowly decompose.
I have a south facing hill that gets absolutely baked by the summer sun. Five years ago, I began to pile branches and other bio-mass on the downhill side of my trees (Asian pears, avocados, figs, peaches, apricots) where the sun would normally cook the soil. Since the tree's shadow was on the uphill side, those piles of biomass kept the soil cool and most on the downhill side.
Over the years, those piles have slowly decomposed and the soil beneath is absolutely beautiful. They serve as a bit of a terrace on the downhill side, making it easier to stand on and pick
fruit. Further, they've become a bit of an incubator for lizards who are my garden friends. The lizards eat snail eggs and little slugs (as well as other garden
pests). So the piles serve multiple functions (soil building, sun shading,
water retention, wildlife habitat) and keep all that
carbon on site rather than going up in a puff of smoke.
Best of luck with your ventures.