I am currently have in stock Orcal 751 and 641 and have a job for a trucking company to do their signs for the truck doors with the company name and DOT #. They don't wont magnetic signs, they are currently buying signs that are done in 3M and are printed on the vinyl. I will be doing the lettering in black vinyl and applying it to a 20"x18" white vinyl sheet. What would be the best kind of vinyl to use as the white. The Orcal I have seems to be too thin to use. What is your opinion about what to use.