Back passenger main automatic window shattered and need a cheap quick fix, any suggestions?

I am not talking duct tape and plastic, so please don’t suggest.

My window broke while I was trying to put a bike in my car, done it a thousand times, but it just was not my day that day. Anyways, I feel like my car is unsafe, like someone may try to rummage through it. Even though it is a beat up car(literally worth nothing to sell it), I do not live in the best part of town. Obviously I removed anything of value, but I am in the middle of relocating and it has been a major crutch.

I talked to someone who was nearby when it happened and he suggested I buy some plexiglass and cut it to shape, and just fix it in place as a temporary fix. I like this idea, but how would I know how big to buy the plexiglass so that it will stay in place. Or, for that matter, how thick would it have to be; thicker than the window glass so it is a snug fit? The window will no longer roll up and down, not sure if that is an issue.

Someone also suggested I call junk yards to find the glass and then find someone nearby who may be able to put it in for cheap or barter(I literally have no $ to my name). I am about to look up how to remove inner panel from door to see what it looks like on the inside.

I live near Mission Beach, San Diego, temporarily. Does anyone have any suggestions? Please help!