Does anybody have any suggestions on how best to purge the air? I have experienced a hard time getting all the air out and fitting it into its stuff sac.

Here's the routine I adopted 30+ years ago using a military "artic" insulated mattress: Wake up. Lie on the bag, open the valve and deflate it using your body weight. Close the valve, get up & roll it squeezing out the remaining air. When your ass hits the snow as the air leaves the mattress you gain extra motivation to get up and get moving. FWIW the best purge comes when you use an air mattress on an aircraft. Deflate before descent...the higher air pressure at ground level will give your mattress a vacuum-packed effect. Be aware of exposed screw heads in the deck of the A/C...they will tear a hole right through your BA. Got a patch on mine that way....

If you open the valve and let it sit for a few minutes it actually loses almost all of its air, making it really easy to get rest out when rolling it up. I usually Open the valve up first thing and then start packing my other stuff, when I come back to it later it is a breeze to roll up. I usually fold the pad into thirds (long ways) and I have had no problems getting it in.

Last weekend I took my Air Core car camping. Since weight didn't matter, I also took along a Coleman battery-operated inflator that I use with a huge air mattress when car camping in the giant tent. The Coleman pumps allow you to take the nozzle off and put it on the intake opening. I did this and used it to suck all the air out of the Air Core. It was awesome! I then closed the valve, folded in thirds and rolled it up. When I got it all rolled up, there was barely any air to let out of the valve. It fit into the stuff sack more easily than when it was new. FKNA!

I don't like to re-use the same old fold lines each time I stuff the mat, because it will continue to wear in the the same spot each time, possibly causing a leak sooner. Not a big deal, as you can just patch, but it's just as easy to switch the fold line locations each time.

Trent This is how I roll mine up. First, I roll it up from the bottom as you would a self-inflating mat. Get as much air out as possible then close valve. Unroll mattress and fold along the creases resembling the way it came from the factory. Now roll it up from the side opposite the valve until the remaining air puffs up the side with the valve. Open valve and manipulate the puffed up side until all air bleeds out. Now it should easily fit in the stuff sack.