Cocos palms for hugelkultur beds

I have been searching for information about whether I can use Cocos Palm stems to make a hugelkultur beds. We are in a very dry climate and I was thinking of planting some fruiting vines over small sunken beds. Each vine to have it's own hole with wood and then soil. I can't dig the area up too much, hence the separate holes per plant, and it is not suitable for raised beds due to the fact the soil would have to be banked up onto colourbond fencing and I think it might cause it to rust.