A few thoughts:
The Compact "family" does have big beds, but on the other hand there is not much open floor space, like there is in the more typical 13' egg. With a dog, that means they're on the bed/couch more than the floor.
The "egg" 13s will have a bit more floor space. You can still trip over the dog, but at least he/she's on the floor! (or on the sofa at the front of the trailer).
Your basic 13-er will have beds of about 76" long. Trillium
has a tiny bit more length, mostly due to square corners, but is basically the same.
With a 2000 lb tow limit, and the three of you plus gear, I'd stay with a very basic (lighter) 13. (i.e. no bathroom, AC, big battery
banks, etc.). Newer trailers seem to be heavier, although that is not a hard and fast rule. I think it's mostly just due to feature creep, not any inherent construction details.
Keep a skeptical frame of mind when you read ads for eggs where the owners claim super light
weights of 800 or 900#. That is very unlikely and I wouldn't trust it unless I had it weighed as such. Not that people are trying to trick buyers; but often they just don't realize.
13s and earlier Scamps (pre-early-80s) have Ensolite walls. Burros have fiberglass walls. I find these preferable to carpet or "fur" walls with pet hair, because you can wipe them down, but there are other folks who prefer the latter.