Ati had suggested something like this before:http://www.uline.com/BL_211/Uline-4-Mil-Reclosable...
If one gets label-less (Sorry Sydney) bags of interior dimensions approx. 9 x 12, no worries about edge folding for the standard Meijer/Ziploc "you can't fit a sheet of paper in here" bag size.
Plus they are cheap in quantity, at least if shipping's not terrible.
But I've gone nearly edge to edge with controls before, so it's easy for that to be an issue I think.
Chilson water looks hard, there are so few places you can readily access by car or by bicycle.
You had a large scale printed, perhaps your map bagger should have been more mindful of it. Your map bagger is also not sure if he should be proud he himself was impervious to scale, or disappointed he didn't even notice!