Gee Mick you have given them a hiding but as you said the china alloy rims are very weak i think steel rims are the way to go for you as you ride over those large rocks on those tracks. And Phil a good billet hub should do the job
How many spokes do the china wheels have? I have some black excel 32 spoke rims I'm selling. I would think they would be stronger than even the steel rims.