Photo mural framing

[freshmanframer]

I have a weird project that I'd love some advice on:

I have 9 13"x19" photos that piece together to make one 57"x39" picture. I think I would like to mount them as three vertical panels, each 19"x39" (3 photos each). This way I can mount them tight together as one big image or with space between each for a slightly different look. I don't think I want to frame each piece because then I won't be able to push them all together and I think it will breakup the flow of it being one big image more than I want. I saw some cool stuff mounted on masonite, but I don't want to shell out hundreds of dollars to mount this, but everyone's saying that just mounting on foamcore will result in warping and bent corners. Also, the photos are glossy and will show fingerprints pretty easily.

I really like the look of this work, but I'm struggling with a functional and good looking way to mount this. Any suggestions? Any photos of examples? Thanks in advance.

[stcstc]

what about using aluminum frames, they can be quite narrow and so could be hung up against each other