I am 100% nomadic. No home. I am often in California and vote here. What street address do I use for my taxes when I only have a virtual mailbox in Oregon?

Since I have no residence, I have no living address or business address.  I work as an artist and do my work all over the world over the computer. I use a mail service in Oregon which receives my mail and scans it for me.  Therefore I have an Oregon address.  But I have an California Driver's License and am in California more than anywhere else.

The tax forms ask for my business street address but I don't have one!  What should I put there?