Hey, I'm pretty new to this and like you have no access to a fridge. My impression from all of the lurking about on this forum is that 4 hrs won't be enough time to cold crash.
I've got an old cooler (doesn't even have a lid!!) that I'm planning on filling with ice (and cider bottles), piling towels and bed sheets etc. on top of for insulation and then cold crashing for as long as I can manage. I think I should get about 18hrs before all of the ice melts. My understanding is that the longer you cold crash for, the clearer your cider will be. Also, the less yeast you will have in suspension so that when the cider warms up the less active it will be -or it will take longer for the yeast to reproduce enough to get the appearance of activity anyway.
As I said, no experience yet, but that's my understanding.
Hopefully, somebody with more experience can pitch in and let us both know how it should go!
R