Thanks everyone for all the info and the ideas. I think that for the immediate future I will try working with the pads rather than trying to install stays. I spent some time packing and unpacking the thing yesterday and can see better ways to pack it.
The G-4 turned out to be bigger than I expected and so for trips without my bear can I will likely continue to use my Jam2. I made the G-4 with the idea in mind of a repeat of the JMT on my soon-to-be 75th birthday; I wanted a light, roomy pack that would carry well and that would hold a bear can. The Jam2 will work but it would be more of a squeeze.
May I walk in beauty.