Hi Craig,
one last effort which you could try before you move on, is a simple rig that was used by Stuart Morgan,whilst fishing the Royalty on a very hot day,we know that at times fishing on some of these pressured waters can be tricky,this rig was shown in Stuart and Guys video,"Barbel even closer."
The rig consists of cutting a groove in a pop up boilie and glueing it on the shank at the back of the hook,the hook length is then weighted to counter balance the bait, all his fish were hooked, and none dropped,this was used when he was in a similar situation to yours,i hope you are succesfull,and well done on your monster chub.good luck.
Brian Willson Throop Bailiff.