In California, that is OK! So long as the job total doesn't exceed $500, which is pretty hard to do. (i.e. stay under that limit.)
I did it for a time before I got my license for side-work. Now I couldn't be bothered with a job that small. (Here Fido, go get that roll of dimes...) Although I currently work for someone else, I also like week-ends and nights to myself.
And your right, not posting a license # with that would violate the avertising rules of the CSLB. So would advertising of being bonded....
"Well - I oughta....." -Jackie Gleason