Just a warning on the inflatable pad – some of them don’t insulate that well (though maybe you have already sourced one that does). Straight air mattresses with no insulation material inside the bladders to prevent air movement will just allow ground cold to transfer to the sleeper.
I used to guide winter backpacking trips and preferred a full length ensolite pad (3/8" or 1/2") plus a short inflatable or compressable foam pad for my torso and head. I have a couple of the Klymit ultra small inflatables now and they work great for comfort with the ensolite and you can practically carry one in a cargo pants pocket. And if you are sleeping on bare ground you probably want something under that inflatable pad to block moisture and prevent damage to the material from sharp little bits of rock and vegetation, so a thin close cell foam will serve for that.
A utility ensolite pad serves many purposes besides sleeping. For kayaking I have a 72" one I cut in half and use one piece inside the cockpit of a couple of my boats to increase fit and comfort. handy for sitting on around camp too. And we even used one along with ski poles to wrap and stabilize a broken leg on a guy who had to be evacuated.
Back in the day, my favorite winter tents all had HUGE floor-less vestibules that we could vent and used cookstoves in during storms. I would usually sit on the folded ensolite to cook out in them.
For a lot of my backcountry gear I eventually switched to “2 is better than 1” for some of it. Besides carrying two sleeping pads, for instance, I found that two lightweight sleeping bags that nest for colder nights have many advantages over having a temp specific single bag. Easier to pack since two smaller stuff sacks can fit in more places in your pack to allow balance distribution and are easier to stash in a canoe pack or kayak hatch. I sold off my winter expedition grade down bags (even the minus 40 F rated one I sewed from a Holubar kit in the late 1970s) and went to a single layer Polarguard oversized mummy bag with a 3 season rated down mummy that could fit inside. Each bag stuffed down to about the size of a large loaf of bread and would fit inside my internal frame pack instead of being vulnerably lashed to the exterior. If I was using the two together and woke up too warm I could wriggle out of the overbag and lay on top of it in the down bag. The polarguard overbag helped protect my down bag from condensation moisture in the tent plus I could stash damp socks and my longjohns I would be wearing the next day between the two bags to add insulation space around me and to keep my clothes warm (even dry damp socks that way).
For day hikes from a base camp or summit attempts in mountaineering, I could pack the more moisture resistant overbag in my summit or day pack in case of emergency bivouac or if we needed to wrap somebody for rescue in case of an accident or illness. Overbag kept my down bag clean too and was easy to machine wash.
You can make a cheap functional hoodless overbag from any old nylon shell quilted synthetic fill discount store rectangular car camping sleeping bag, even one with a busted zipper. Just lay your down mummy bag on top of the inside out cheap bag and trace an outline on it about 4" bigger than the mummy sides and bottom edge with a Sharpie. Then cut both the top and bottom layers on that line. Use a lighter to carefully singe the edges of the nylon so it won’t fray and sew the two layers together across the sides and bottom. if you want to get fancy you can stitch bias blanket binding from a sewing supply store over the raw seam to make it cleaner and not scratchy. And you can add a half or full length zipper to one seam, though my overbag has never had that and has worked fine as just a quilted oversized sack.
Another advantage of carrying duplicate items on a group trip is you have a spare to equip someone else who may discover they have inadequate gear or lose some or all of it. As a guide I had to consider that kind of thing but have retained the habit.
And you never know when a piece of your own kit can fail or get lost. i know somebody who fumbled strapping his stuff-sacked winter down bag to his pack at a steep camp 2/3rds of the way up Aconcagua (highest mountain in the Western hemisphere) and it bounced halfway down the route. The expedition had no extra bags so he had no choice but to abandon his chance to make the summit on the trip with his team and had to hike back down to find it. It was 3 hour descent before he located it, fortunately the bright blue stuff sack stood out clearly against the grey rock and ice and it had not gone into a crevasse. That bag happened to be the Holubar arctic bag I had made, which I had loaned him for the trip. One of the other climbers, who watched with him in dismay as the packed bag bounced down the cliffs, told me the first thing the guy who lost it said was “Kerry’s gonna kill me if I don’t get that back.” He did comment to me when he confessed to the disaster later that maybe if I had not sewed such a bombproof stuffsack for it (triple stitched cordura) maybe it would have exploded on one of the cliff drops and released the bag so it would have stopped bouncing further down. Oh, well…