I live near Universal studios and can't say for sure what their policy is on overnight parking. But I don't know if I would recommend doing that anyway. Let's just say, the neighborhood takes on a completely different characteristic after hours.
However, there are some RV parks, not far from there that are quite reasonable. If not, here's a link I came across recently that may be of some help...
http://www.freecampgrounds.com/results.aspx?rg=0&s=13&st=0&co=0&h=0&rd=0&mf=-1&md=0&ns=0&sc=0&nz=0&n=&c=&start=1
Barry
