I am familiar with RAL. What viral tests are you looking into? What laboratory processed any previous viral tests?
I do have to say I have very mixed feelings about viral testing with commercial labs these days as results are not super reliable. There are a couple of university-based labs I would trust.
Perhaps more importantly - keepers panic if their python tests positive for Nidovirus, for example, and assume that it's a death sentence. But the reality is that it's starting to look like many snakes may carry the virus for years, and perhaps throughout their lives, without ever becoming ill at all. An asymptomatic positive snake may live a perfectly normal life.
Your snake has not been showing any of the symptoms of illness associated with either Nidovirus or IBD (arenavirus) and has not been exposed to other snakes that could have transmitted. So I'm not sure that a viral test will really tell you anything, regardless of what the results turned out to be. If she has somehow been positive since she was a baby then she's also been asymptomatic, so the focus wouldn't be on the fact that she's positive - it would be on providing her with the best possible quality of life to ensure that the virus never becomes an issue.
Her body condition looks very good, including the overall iridescence of her scales. I don't keep the large pythons but a 350g meal for a snake her size isn't enough. I just suspect that this is a combination of the snake needing a bump up in food plus providing more exercise and enrichment. Depression and lethargy in captive snakes is a real thing.
She's in a very bare enclosure that lacks environmental complexity and enrichment. It's great that you let her out, but she is a large, intelligent, semi-arboreal snake. These snakes are smart and athletic and she needs more - if her enclosure has been like that throughout her life, then it may take some time for her to fully respond to and engage with a more enriched environment.