You dont need to have doors, removable or non removable its all the same. Last year I made a call to the DMV to ask them, they didnt have the answer an said to call CHP cause they would be the ones to give you a ticket. I called the CHP an asked the guy that answered the phone, he first kinda laughed an said to me, I just took mine of for the summer, yo dont need to have doors as long as you have mirrors.
If you are worried about it, just make half doors.