A Kumo is the same pattern as the Murmur,' cept more durable cloth is used.
The outside pad pocket works for a pad keeper. The limitation with those packs is the thickness. The thickness determines how many layers you can add. How many layers determines the length of the pad. The most I have been able to get in the pad pocket is about 2.5". This means that the center of gravity is pushed outwards, but, with the light 20pound loading, this isn't much of a problem.
I use a 5 layer NightLite pad cut to nest the "bumps". This means you can get them into the pad pocket. The caveat is you might need extra long shoulder/hip straps. The 5 layers comes to about 52" all told. Each segment is cut at 10.25". Fanfolding and nesting the bumps means the nominal 3/4" pad only needs about 1" for two layers. After 3-4 uses it will squash down to about 2.25" total…it gets easier to pack. The duct tape holds up pretty well, at least 60 nights. It will also act as a good frame for the pack when hiking, doing double-duty.
Anyway, you wanted attachment points for a pad/tent.
I DO NOT recommend opening the seams. Between the factory stitching, and the biasing tape used inside the GG packs, this can turn into a lot of work. I use cord for loops. Paracord is a bit heavy. 1.5mm cord is about right.
Get some self stick nylon patches from the sewing shop and to reinforce the area you want the loop inside. The self stick is easy to work with, it stays put. Choose a location about 1/2" away from any factory seam. (This might be a good time to reinforce the factory seams inside with a second row of stitching about 1/16" away from the factory seam. Especially the shoulder harness/strap mounts.) After choosing a location, poke a pin through it to insure placement inside and mark center on the outside with a marker.
Stick the patch on and sew it around the perimiter. Then stitch an "X" across the inner surface of the patch. The goal is to create a reinforced area of nylon/pack cloth about 1" to 1-1/2" square.
Carefully mark for two tiny holes about 1/8" from the center mark; left & right, or, top & bottom…it doesn't really matter.
Then heat a paper clip with a lighter and punch the hole, working it around to expand it to about 1.5-2mm. If the paper clip is very hot, it will open by itself. As it cools, you can work around slightly. Do the second hole. Do NOT clean the slight build up off…it will act as a cheatin' growmet. The ends will all be heat sealed so there will be no fraying, and, the two pieces of fabric will be sealed together at the holes, reinforcing this area.
On the outside, you will end up with 2 small, growmet-like holes(about 2mm-the size of the cord) seperated by about 1/4" material with the "X" from the reinforcement patch stitching passing between them. This is sort-of precise work.
Pass your cord through the loops and tie it off. The loop itself should NOT hang out beyond the bottom of the pack. Setting it down, they can catch on leaves and other debris. Large loops can catch on branches or sticks while bushwacking. Keep them small enough to avoid this. After tieing the cord loop off, heat the ends to melt them and prevent them from coming loose. If you are worried about waterproofness, you can seal these with a dab of silicone caulk, inside and out.
I don't care for floppy things on my pack, so, you will probably need four loops on the pack to stabilize any load placed there. Using a seperate cord on each loop lets you use them for whatever you want to. Tying the loops together will act as compression on the pack.
It will add about 1oz of weight. Worth it, if you need have the extra space available.