Yeah, I can see how it would be difficult. I would split it down to two pieces 20″x60″. Most packs can handle around 11″ wide, some can handle 12″ wide, others can only handle 10.5″ wide, soo, Measure Your Pack! You might have to cut down the length slightly to the nearest increment of your pack measurement. A 60″ pad, fanfolded and taped at 12″ wide will cover 60″ even if the evazote is flat on both sides. If it is dimpled (like Gossamer Gear NightLight’s) you will need to fanfold a slight gap leaving it about 62″ long (to keep all the dimples on one side.) You can fit the folded pad into the back of your pack, or, on the outside of your pack in pad keepers. If you use it on the inside be aware that it will take up a lot of room…12″x20″x.5″x5layers or about 600ci/9.83L. The pad keepers on the GG packs will *just” fit a 600ci pad. (The first couple times will be tight.) For two pads it will take close to 20L in your packs space. I have been doing this for well over 12 years.
As a summer option, it works really well. For full pack support (instead of any frame,) both the top and bottom need to be well supported in your pack. I highly recommend you using this on the outside of the pack and save the interior real estate for other things, stove & pots, food, cloths, etc. But, I also carry a 35L pack for a couple weeks out. Or, roll them around the perimiter on the inside of your pack. But cubic inches are still cubic inches inside and I dislike the “tube” effect for carrying.
I could never figure out another way to carry these pads except to roll them up and put them on on the outside of the pack which I dislike intensely. It was always catching on something, snagging on brush & scrub, or otherwise making the pack awkward to carry around.