The only barbel I,ve ever deep hooked was caught on a chunk of meat, fished on the hook in very deepwater (26ft), couldn,t even feel the hook, no chance of unhooking, probably lucky it didn,t bite me off.
The use of knotless knot type hair setups make deephooking near immpossible, they hook on ejection of the bait, the weight of the bait is enough to at least ***** the fish, without any additional weight, so long hooklengths are no problem, boltrigs are just not needed, you will get a full on 3ft twitch even with a freelined bait, try it!!!!!
peter