I haven't logged in here for a while, so sorry this is such a late reply... we used about four quart cans on the trailer.
Thanks for getting back to me. We have proceeded with the interlux product since my previous post. We ran into a few problems and ended up purchasing a totally of 1.75 gallons. I'm very impressed with the color of the product, but unlike others on this forum I'm a little bit unsatisfied with the finish results. Maybe I'm a bit to picky, I'm not sure. I'm used to dealing with automotive spray finishes and we ran into to many problems with dust, and remaining streak marks from the tipping process. I believe we followed all of the recommendations and application instructions per manufacturer but we just weren't able to produce a finish that I'd be totally satisfied with. For now it will have to do, and the next time we will have the unit sent out to a local spray shop with a downdraft booth to do the application.