What bag are you planning on using, standard bar roll? If it’s a one off then a couple of those alu handlebar extender things of eBay/amazon to mount lights etc could to the job to brace the bag against.
If you want to invest and don’t have a bag already could look at the salsa handlebar (EXP?) cradle?
I will likely be using an Apidura handlebar pack and accessory pocket and need to look after a loaner that I won't receive until a couple of days before I ride it, so no time to do much in the way of experimentation.
Guess one of those cheap eBay extenders is worth a punt.
What bag are you planning on using, standard bar roll? If it’s a one off then a couple of those alu handlebar extender things of eBay/amazon to mount lights etc could to the job to brace the bag against.
If you want to invest and don’t have a bag already could look at the salsa handlebar (EXP?) cradle?