REI Flash 45 + SoLite Ridgerest Short

Since the Flash 45 has a pretty flimsy frame I think putting the pad inside the pack is a good idea if it will fit. You might try rolling it up loosely an putting it around the outside of the pack. Pack everything inside that.

On one trip I tried folding my RR and it was too bulky. Then I tried rolling it and it was fine.

Putting it on top under the lid might be another good strategy. When you stop to take a break you can just sit on it.

Luke, thanks for the tip – I'll try making it into a cylinder for a frame and see how it does.

If it doesn't fit inside, I'd probably go with under the lid.

Rolling it is more space efficient because you should only one or two layers of foam. Its pretty easy for the stuff inside to push the foam out so very little space is wasted. A folded or tightly rolled pad tents to waste some space.

I should line the pack with it or stick it on the outside somehow? I think your post said outside but I was thinking I'd line the pack with it…inside or outside of my trash compactor bag? Ha, I'm having trouble visualizing this for some reason!

I think he was suggesting what you had thought of: try sticking it inside with the trash compactor bag inside of the "burrito" formed by the mat. I roll a mat tightly to stick it easily inside the pack, then start unrolling it and letting it unravel to fill up the very edges of the pack.

If it won't fit inside I'd try under the top lid.

Sorry I wasn't clear. The rolled pad goes INSIDE the pack. But the pad will be up against the walls of the pack. Does that make sense? Your pack liner can go either inside the pad or outside it. I doubt the RR would absorb much water if it rained.