I can't help you with the application of the numbers, but would caution you about adding them. Some folks are planning or have attached the numbers to a piece of plexiglass and display them from the window.
The problem is that with the older units, when you want to strip down the ext and and polish it, the numbers come off. Additionally, on new coaches, some folks (including me) don't want to mar up the finish with the numbers. One reason could be if you decide not to be a member and then taking them off can be a pain, plus, there will be a shadow of the numbers until the coach is stripped an polished.
In the end it's obviously your call, but I would vote not to perm attach. I know some WBCCI folks cringe by those words, but I don't plan on sticking anything on my coaches exterior that does not have a function.
