Hey John, that looks pretty slick, what does the whole assembly weigh? I looked around at a bunch of materials last year to make a framesheet (carbon fiber sheet, HDPE, etc.) and couldn't find anything that weighed less than about 8oz. I think a framesheet is much more comfortable than a closed-cell foam pad in a backpack - it keeps the pack body from bulging out when you stuff it and protects you from lumpy items. I have a HDPE framesheet from a commercially made backpack that I used to put in my Ohm when carrying a bear can as it kept the back panel flat instead of bulging out from the cylindrical can.