Weren't they? I have been searching for info on this, and started compiling a list for myself. I'm just starting my classic bike journey, and not very knowledgible, but..
So far, just a few names, ...
The Schwinn "kingsize" cantilever framed "American" and "Heavy Duti. No info on model years.
A variation of the Cleveland Welding made "Roadmaster", which included the '90s reproduction "Luxury Liner".
- One variant of CWC frame was said to be more suitable for larger riders, not because it's taller, but because the top bar is longer and the seat post is angled back a bit more.
I'd expect that going back to the prewar days, there might be more candidate machines with more spacious frames. I thought of starting a thread on this topic, but it seemed prudent to do more research first.