Fluid film rust treatment

We have a business about 25 miles from my house that does cars and trucks. A level 3 on my 3/4 ton is 300-350.00 and the pull the taillights and and plugs. And of course the whole bottom. They quote 3 hours but if you are going to wait he will put two guys on it and have it in 2 hours. That’s what I would have to do. Because of the salt and salt brine already on it the spray it with a neutralizer first.