10 mils Silver Plate

Old timers from the aircraft industry used to plate silver that thick. You cannot use metallic brighteners that contain antimony, selenium, or any other metal. You can however, use the old carbon disulfide type brightener.

I do not know whether I can mention proprietary info here, but if I can, the "Industrial Silver Process" from the old Sel-REx Corporation, now Enthone, was fully capable of 10 mils. It used a 10 tr oz/gal solution. Back in the '60's we laid it down that thick at Delta Air Lines and Pan Am Air Lines.

Yes it is possible. It has been used for a number of years as a bearing material, but with silver at 16 - 20 dollars a troy Oz, it is relatively expensive.

Depending on the shape, you will probably have to do a post plate machining if it has any significant tolerances.

Some people can get by with shields and/or conforming inert anodes.

I can not see it working with anything other than a cyanide silver bath.

Not a simple operation. You probably will spend a lot of hours finding the optimum way of doing it which has to be included in the contract price. Personally, I would make sure that I could do it before I took a contract for the job.

You will only have to leave the parts in the bath longer. Ten times longer than you would for a thousand. Regarding the cost of silver, I don't think you should worry, he will have to pay for what he's buying. Either to you or to someone else.