I just had this problem coming to Maine from PA, the biggest problem was all the places I worked had no real liscensing. Luckily my apprenticship was "Nationally Recognized" or else I would have had even a tougher time. Just make sure before you leave you get all the documentation you can, as Leo stated get all the guys you worked for to sign off if you can or as many as you can and get letters from the companies you have worked for before you leave.
Have them include your job title (apprentice or whatever), a description of work performed (doesnt have to be detailed but more the better), how long you worked for them, and that should cover you pretty good. As for you length of service that is the one that helped me with my hearing here in Maine, they figured just from the one company I had 12000 hours with out overtime, so I won my appeal just had to take the code update course. Oh, and when you do an application for a card or liscense include all your certificates for all the things you have done even if you think it does not ask for it.
Good luck