Just got back from the vet with Sassafras. I was correct, she does indeed have some large ovarian cysts, and a slightly elevated temperature. It's going to be a complicated spay so they estimate $800 for it
but they take Care Credit so I'm going to apply for that to spread the cost out a little. She was so well-behaved for the vet though, such a cuddle bug. They think she should do well with the spay as she is otherwise strong.
I suspect the mother (Pepper) may also need a spay sometime in the near future, as the vet pointed out thinning hair as a sign of the cysts, and Pepper's coat is looking a bit thin in places as well. I wasn't sure if that was normal for a texel but now I know it's not. So she's next on the docket for a vet visit.
So, perhaps all is not lost yet on the housing situation.
My partner has come up with one more avenue to pursue (an online service that connects you specifically with mental health professionals that prescribe ESAs, including legal exotic animals) so I have made a virtual appointment with them. It's apparently hard sell that guinea pigs are a valid ESA species to people who are not familiar with them and think they are just large hamsters (not that hamsters couldn't be valid too if one was very attached to them, why not) so hopefully this fellow has some familiarity with prescribing them. I'm rehearsing on everything I do with them in a given day that helps provide me with comfort and structure.
And on a totally unrelated note, my mother has offered to take me shopping for some curtains that let in light but block prying eyes, how nice of her.