how will be traffic divert to your client web? capture the mid point use referral links, & the respective tracker services will be track out the referral link....
i think its solid proof for maintain your business goodwill on-front of your valued clients..

let example i got contract for delivering 1000 X traffic on my client web... my client web link is http://www.xyz.com i created link forwarding links its simple....client will able to see your links...