I'm in the building trade too, done a bit of flushing around my own home but not one of my favourite jobs. Sorry I don't know of anyone that does it for a living, from what I gather they are hard to come by. I hope you find someone but if you decide to do it yourself it may pay to hire the right equipment. The hire places have sanders that are on a long handle and they are almost dust free, I wish they were around when I did my house.
Brian
Cobra PF