Big Agnes has one where their sleeping pad slides inside a sleeve on the bottom of the bag. Never tried their sleeping bags but I do have one of their sleeping pads and I personally think it is hands down much more comfortable than any Thermarest I've tried.
FWIW,,,, I too have this Wiggy's Sleep-System for Base Camp Use Only, and "Yes" you will "Love it".
For Spiking out, I pack a "Closed-Cell" sleeping pad, a light tarp/shelter -[6'w x 8'L]- called a "Manny" and my Insulated Headware & Gloves, Insulated Coveralls, w/integrated hood. I was shown this Tactic quite a few years back, while Sheep Hunting in the Absaroka-Beartooth Wilderness in Montana, as it was told to me at the time by and old outfitter, that it was a lot easier to "Walk" in the coveralls, then it was,,, trying to "Walk" in your "Sleeping-Bag"-:topjob:
I have a synthetic marmot 0 degree bag. I've used for everything from kodiak 2 week spring bear hunts to winter camping in -20. With a proper pad it's amazing. Wiggys is good for a drive up camp to bulky to pack anywhere.
Whatever you get, I'd recommend down over synthetic. Down has come a long way over the last 10 years such that, it no longer suffers from big decrease in performance when wet, which was a major selling point of synthetic.
I also have the Wiggy's but got the Kafaru mod quite some years ago that has a different cover on the main bag. While still a bit bulky I have done a ton of 3 season backpacking with it. Add the outer bag for winter and it definately becomes a vehicle mounted system.
Talk to Marc down at Wiggys I am pretty sure the glacier hunter series has a similar cover to mine.