6x9 speakers in an FC vert?

[Max777]

Ok, so I got a pretty beat up FC, and it came with like, the MOST ghetto stereo install I ever saw, and some 6x9 Pioneer speakers in these weird box things that were just laying around in the back area with some wires hooked up, with absolutely NO hint of actual mounting. Right now, I took all that shit out, and just have the door speakers and a gaping hole in my dash with the factory plugs sticking out.

Now, I want to put in my old headunit, but these dont really look like they want to fit anywhere withought a lot of work, and the stock S5 vert speakers/plastic sround things are gone from that low area behind the seats. What should I do? I'm a total noob at speaker installs, only installed a head unit before.

Would it be too hard to make a small box out of plywood or something? And, how far away do the magnets on the speakers have to be from any metal? I was thinking of a flush mount setup in the spare tire area of my vert, since I dont have a tire there anyway?