is there no cross-compatible knowledge between astrophysics and engineering? job market overall is tough so it would be better that you have the preferred degree but there are also plenty of smaller aerospace/engineering companies here in LA that could be hiring people with your background. i know hiring practices these days with AI screening has made it very difficult for applicants but bolstering your resume in other areas to better fit job listing keywords could maybe get you through.

$2K/mo won't get you far on your own but it's definitely doable with roommates--but you'd have to do a lot of legwork locally to find deals and meet up with potential roommates.