If the customer is going to take this on the chin for you then you are very lucky. Legally, whoever hit it is responsible for the damage, and that is why many of us on here make as many precautions as we can to avoid service strikes as it costs more than we charge for a days work to repair.
I get the idea of the Rhinox bucket but if you are digging like a mad man, it wont help anyway. Correct technique and some experience with reasonable guesses combined with a CAT and Genny should see you avoid most buried services. All my buckets under 450mm have the teeth removed and if you are digging in an area of suspected services then I always dig in layers. This allows you to see a possible change in soil type which could show up a trench etc and if you do come across a service, you have a good chance of just skimming over it rather than ripping through it. Yes it takes more time but its a lot cheaper than hitting the thing!
I appreciate services are rarely at the depth they should be, I've found HV under a skim of tarmac, NTL under an inch of grass, BT in the haunching of path edgings, and sometimes they put them in the sky too! (yes that's a telegraph pole that's been pulled over by a passing delivery lorry catching the cable - not me who caught it - I just happened to be under it at the time!) My point is, maybe they didn't put it in right, maybe the ground levels changed over time, none of those reasons is an excuse for striking services.
Arm yourself with as much knowledge of where you are digging as possible, having a quick look around can often give you an idea what might be lurking under - water meter covers, maybe a cable coming down from a pole and disappearing in the ground? All want investigating and my biggest lesson I learnt - dont trust the customer when they say there's nothing there!!! What do they know?!