4'x8' is pretty big. I'd think about finding a way to make it sectional.
1) Most door ways aren't 4' (you could have the proverbial boat in the basement)
2) It is much easier to work on something, or make an adjustment/repair/addition if you don't have to hang over something to get to it. (there is that whole Tom Crusie harness contraption from mission impossible...)
3) If you ever want to transport it somewhere....
4) Cleaning it is going to be a chore, as it will collect dust, lint and other goodies, on under and around. If you can move it it will make it much easier.
5) Acryic in length is expensive. The more you can make it sectional the less expensive it will be. Even if you make your longest edge 4' that is still a pricey piece of acryic or lexan. If you leave it open on one side to show off the bottom topography, how are you going to dust under there? You will essentialy have a 3" by 4' or 8' slot.
I do hope you will be posting progress pics. Despite my misgivings about projects this big, it sounds like an ambitous and definately worth while build.
Good luck with it.
Mike
"Imagination is the dye that colors our lives"
Marcus Aurellius
A good friend will come and bail you out of jail...but, a true friend will be sitting next to you saying, "Damn...that was fun!"