Anyone keep box turtles?

[GoingPostal]

My neighbor asked if I'd be interested in taking in some turtles from someone. After some questions it sounds they like are 3 toed box turtles. The tank they are in looks small and apparently they are fed calcium dusted lettuce once a week which doesn't sound ideal either. Outdoor enclosures seem recommended but idk that northern MN is suitable for that very long. Should they be brumated? I'm seeing way varied advice on temps, feeding, housing for these guys and not sure what I might be considering. They are 10-15+ years old, passed around every 5 years it sounds like.

[Malum Argenteum]

I keep 3 three toed box turtles currently, 2 males and a female. I lost one last year -- heatwave (when they were in their outside quarters), that I thought they could deal with. This was a turtle that was one of two that were rescues (more or less -- I offered to take them at wholesale cost from a shop that had no clue), and was never the healthiest of the group. About five years ago one escaped from their outside quarters after I nicked that enclosure with the riding mower and bumped it off its foundation far enough that there was a gap big enough for one to slip out of. We've had them since about the mid-late 1990s, and they're all wild caught (do it again, and I would buy CB, of course).

In winter, I brumate them for three months or a little longer. I put them in a tub full of damp peat in a basement that maintains about 45F - 50F. I'd like that a bit cooler, but those temps are OK. Before we owned a house we brumated them in a mini fridge, and that worked fine.

During the time they're awake but it isn't warm enough outside, they live in a 4' x 2' PVC enclosure with added ventilation. The female has been relatively intolerant of other turtles for the last year or so, so I have a divider in that enclosure. The males don't get along all that well either, but they do end up working it out. I give them UVB (~ zone 2 throughout about half the space), and an even temp of about 75F, a little cooler at night. I use repti chip for a substrate since it is convenient, which I add a good amount of water to each morning (I should put them on a mister, really).

During the summer they have a wood and screen enclosure that sits on a brick foundation, which is about 5' x 7'. It catches some direct morning sun, and then mostly dappled shade during the day. I'm in Central Wisconsin, so the outside season is late May into September. As long as lows don't go beyond the low 40s, that's pretty good. Especially in fall, once the overnight temps drop, the turtles dig in and are very hard to find.

They're actually omnivores, leaning moderately heavy on the meaty stuff. I try to feed about half meaty things (superworms, hornworms, earthworms, roaches, the occasional FT chopped pink mouse), and about half plant matter (greens, finely chopped carrots, some fruit). I dust everything with Repashy Calcium Plus.

They're statistically higher users of vet services than my other herps, so be prepared for that.