@SevernRat glad to help. Again, having your wife skiing at 28 and hopefully your daughter getting excited about skiing rings true to my background. My wife has been learning the course the last few years and skies at 28. And my daughters skied at slower speed during their learning years. And I teach a lot of female skiers the course at our lake house, so I care a lot about slow speed wakes.
The ski wake at slower speeds is something that varies quite a lot by boat model. Also, the fact that you're skiing with full rope length may be significant as well and frankly I don't really know what the wake is like at full rope length on many of these boats. But it may be better.
Our Ski club upgraded from a 196 to a 200 in 2014. The 200 has a better wake at slower speeds than the 196. I also have a 2019 ProStar for slalom course skiing at our lake house. It also has a good slower speed wake.
Given all you're said, I think a Sunsetter or Response LXI, may be the best balance point for you as others have also suggested. It has the advantage of having a higher freeboard than most of the other slalom boats so should give more of a margin weighting the boat for wakeboard and surfing. Net, I could see it being the right balance for what you want, but the slow speed wake is little bit of an unknown for me.
I've only skied behind the 197 / X7 in a tournament, and I wasn't that impressed with the wakes. But at the time I was skiing 15 off and 30mph, and the 197 is known for having a respectable slalom wake at higher speeds and shorter line lengths. The 197 also has a reputation for being a great trick boat because the wakes get bigger as you slow down, so I tend to think it wouldn't be the greatest option for your wife / daughter.
Having owned and used both a 200 and newer ProStar on both private, but more importantly on public lakes with other surf boat traffic, I can't imagine feeling safe ballasting them for surfing.
anyway ...just my 2 cents, but I doubt you're going to find many people that have first-hand experience with all these boats, especially the characteristics at slower speeds and full line length. Ideally, if you can find something and are able to test it out, I'd recommend having both you and your wife try it and see what you think. If you're happy with it, that's all that really matters.
I'll also add that if you're a tinkerer, a surf boat can be pretty addictive. It's the ultimate toy for someone that likes to tune and improve things. The other thing that I like about surfing, is it's really very social. You can take 10 people out on the boat, and even if they have little experience surfing, most can learn to do something first day out. And all the action happens right there within speaking distance, so the boat full of people tend to get very engaged. Slalom skiing will always be my first passion, but when you have lots of time to burn on a big lake, it's hard to deny the appeal of surfing.