Since nobody else has chimed in, I will toss in a comment or two and then wait for wiser folks.
I am suspicious of Vivak in larger sizes. It is already kind of flimsy in 1 sheet size and would have issues as you get larger. Based on my reading, I think it is produced in 51" rolls, so you may not be able to get it at any rate.
IMHO, Sue is giving good advice. I have framed 3 sheets, and I found I needed to go with a thicker acryllic, at least 5/16". A foam backing is the minimum, and I have mostly used masonite with a barrier layer. Heavier, but it stays put.
I have a couple of Thierry hates "French Grande"s and a Bus Stop for a Broadway play I am considering hanging, and I have been thinking about mounting directly to the wall. I would use the foamboard backing, acrylic glazing and then notch 1x3 stock to support it. Drill holes through it and place into wall anchors. You can hide or highlight the screws by either using decorative brass, or by countersink drilling for plugs.
I like the spotlight displays, but I think they work best in smaller sizes. They are difficult to manage as you get larger, and the posters tend to slip out. If you want a larger size, I would go with Sue. I'm not sure she ships something this large though. If you live in Southern Cal, no problem. Otherwise it might be best to look locally for the glazing, and then buy the rails online. Grafik Dimensions (
www.pictureframes.com) is a reasonable source of rails.
Non-glare glazing is purely your call. Costs more, but it makes a big difference in viewing angles.