Definitely make a build log as that sounds quite interesting! The way I figure it, it comes down to eliminating the bezels. But is the bezel problem really that huge of a deal? Granted, of course we would all like bezel'less curved screens of perfection. But you have to go a long way just to eliminate bezels.

Take my setup for example. Yes I've had to do quite a bit of custom work to get bezel gap's less than 1/4 inch. But that small of bezel's really isn't noticeable when playing games. Granted, when they come out with a 40" 4K true 120Hz OLED monitor my multi-screen days are over!

I haven't really looked into projectors in a few years. Are LED light sources putting out decent pictures? I remember just a couple of years ago they were pretty much garbage in projectors.

My largest "issue" is the 720P. That is a pretty darn low resolution. The only way I'd personally consider that resolution was if I ran maybe five of them in portrait with edge-blending hardware. But of course no edge blending software/hardware is perfect and will "blur/distort" where the images merge. Some say that can be as distracting as having a thin monitor bezel.

3x 720P/800P screens are only 3 mil pixels, or about 50% more than a 1080P screen. But like you said if you plan to sit around six feet away, the resolution won't be as big of concern. But then again you will lose some of the "immersion" factor of sitting closer. Text might be an issue on that large of a screen.