I need a 16 ft x 16 ft in the same material and features as the 8x10....Can do?

I've seen 12x12 in Silnylon pretty commonly, but never 16x16. Maybe the cost is prohibitive (I'd think it would be $300-$400 or more). Maybe structurally it is hard to do, too -- suspending the tarp's weight over a longer ridgeline? There's a version of the Kelty Noah tarp that's 16x16, but it's not Silnylon. Truck tarps and canvas tarps are also made at that size.

You could try REI or something for a bigger one and cut it down, Backcountry doesn't do custom tarps. This isn't Backcountry brand gear anyway.This is a good company for on the shelf items like you're looking for. No special production or "cut to size" necessary. Hopefully the 15'x15' will work for you needs.http://www.boundarywaterscatalog.com/browse.cfm/4,5442.html