Hmmm, don';t know about hazmat addon. Here in California, I have a PO Box on my license, get me important mail at the PO Box and have used it for everything legal or important because we lived out in the 'sticks' where security was a rancher in his 4 x 4 with a rifle! I never had any problem with the CDL.
I have three kids that live in Calif too so if I had to use a perm address, I could use one of theirs.
At the very least you might have to make an appearance in a local DMV office but that wouldn't be so bad. Best advice I can give ya.
Hope it helps.

db

Hi, I read your blog about renewing your commerical drivers licence. I too have a CDL issued in PA. and would like to cruse and keep my cdl so I can work 3-5 months a year. I was told by my boss (of all people) that you need to have a permanent resident to hold a CDL with hazmat. Can you please tell me how I can legally keep me licence and cruse without having a permanent resident? What is the best way to keep getting my mail or keep my car registred?? Thanks Viking Blood