Alex-"I can't believe there's no single wall little bomber tent out there for a guy and his dog at 2.5lbs packed weight."
Of course there are, plenty of them, but I thought you were trying to use up a 20% off coupon at REI! IMHO, the good tents, especially single-wall, nearly all come from the cottage manufacturers, not the big nation-wide traditional gear dealers.
For a couple of years I used a Tarptent Squall 2 (34 oz. including stakes but not pole if you don't use trekking poles) which is palatial for one human plus dog, plenty roomy enough for two humans plus dog, and so well ventilated that internal condensation (even during an Olympic coast drizzle) is a real rarity. In fact, the only time I've had inside condensation was when I pitched it in the middle of a meadow on a below-freezing night, and that was just a bit of frost up by the ridgeline. I still use it for taking out grandkids (one at a time)! Tarptent sells poles for it if you're not a trekking pole user, probably another 1 1/2 oz. for two of them as they recommend.
Then, in my quest for less weight on my aging knees and feet, I tried something lighter just for dog plus me, namely the aforementioned Six Moon Designs Lunar Solo, about 26 oz. with stakes but not pole, unfortunately too small and definitely not well-enough ventilated. My current tent is the lovely but pricey Tarptent/Gossamer Gear Squall Classic (designed by Tarptent, sewn and sold by GG, same weight as the Lunar Solo), perfect size for me plus 80-lb. dog, enough room so we don't feel squashed when confined to tent by a cloudburst. Although theoretically a 2-person tent, IMHO it's more like a 1 1/2 person tent. I wouldn't recommend it for two adults unless they want to be really cozy together. Only one can sit up at a time (not a problem with my dog and me). You could also try the Tarptent Contrail –lots of those going on sale used right now as everyone who had one seems to be getting the Moment. (I did some calculating and the Moment, while more streamlined, is just too small to include the dog unless it's a very small one!) I know several people who share their Contrails with their 70-90 lb. dogs. Or the Tarptent Rainbow which is a 1 1/2 person tent, a little heavier than the Squall 2 but doesn't require a trekking pole, has more interior space and can be rigged to be free-standing, if you want that.
By the way, the dog wasn't with me on the Olympic coast (Shi-Shi Beach), obviously, but my then 8-year-old grandson was!