85 botteccia, 85 mcmahn tiatainium, 90 something trek clyde, early 70s schwinn tandem single speed, early 90s gary fisher aquila (the daily rider now!)
Do you know if your dog likes trailers? That could be a issue. My girl loved them making it great to take with. I had a burly flatbed and made a wood deck covering the whole frame then added sides and front. I'd be cautious clamping to a carbon fiber frame but probably feel real comfortable with an aluminum frame.
I ride a Trek Allant (aluminum frame) and have used it with a converted Bell trailer to haul my dogs and groceries. It is my go-to bike for almost every ride. My husband rides a KHS TR-101 (Cromoly steel) and he'll haul 100+ pounds using a custom-built trailer or the Bell trailer with pups on board. We find that both of these frame types are more suitable for the type of riding we do and the roads we ride on (dirt in some areas).