Indeed, the only thing that could make it better is if issues were integrated into git somehow. Maybe just another branch similar to wiki/gh-pages?
It's probably even simpler to use the hosting site for Fossil at http://chiselapp.com/ It's advertised as a free service and houses several hundred publicly accessible sites. Kind of like a low-key GitHub for Fossil repos.
How well does Fossil scale? SQLite (https://sqlite.org/), "the most widely deployed SQL database engine in the world", can't be too small a project. Certainly a nice-looking site, under its skin pretty much a plain-vanilla web-facing Fossil repo.