After some poking around and researching what it would take to write a fixture that did what I was looking for, it seems like FitLibrary’s DoFixture is close enough for hand grenades, at the very least. Many thanks to this guy for his post pointing me at FitLibrary. I probably should have known about the library (it is in the FitNesse User Guide after all), but sometimes it’s hard to see the trees for the forest!