I think the whole circus thing was supposed to be a joke and not really meant to be taken seriously, like the time Peter provided heat to Lara Flynn Boyle by becoming her blanket. And 2's can also be nurturing and sexual in a "bad ass" way, though I don't get that vibe from her at all. Besides, like I said, Lois is much too submissive in many instances to be considered an 8. An 8w9, for example, would put their foot down if they're getting demeaned and ignored by their spouse, such as when Peter commands authority over her in front of the kids during the karate episode and shuts her down, or when she chose to binge on food to get back at Peter for ignoring her sexually instead of confronting him about the issue. Yeah. Definitely not something an 8 would do. She has a wild streak, yes, but that has to do more with her just letting loose and getting caught up in the moment rather than it being from a core motivation.
At the end of the day, Lois is too much of a caretaker to be an 8. She's not very ambitious and doesn't care about controlling others. She's perfectly content living her small little life taking care of her family, entertaining her neighbors, and occasionally, teaching kids how to play the piano.