Pinot I've had the two boars narkiness like you describe.
A combination of the change of scene and being in each others faces.
My pigs have a Pighouse they use the whole floor space but naturally tend to snuggle in the haybox.
I did notice with our first boar pair that if hey are chilled, they will cuddle up in hay but not together. They squarely sat in their own corners (they evidence of pooh nests confirmed this)
My little boar GP2 was very unco-ordinated one day (sport of rolling) I put him on the ramp and he practically staggered down it. (Course I was in panic mode 
) but it turned out he was stiff from sitting in one place.
So we make sure their floor was covered (soft straw or equinine bedding cardboard stuff).
At the moment we're onto GP4 GP5 (two unrelated sows) and GP6 (neutered boar)
They have been inside on cold nights , they were last night. I have a 4'x2' cage which isn't big enough for 3 adults but I've tried C&C runs indoors (worked well for our boar pair GP1 and GP3) . But the boar/sows cuddled up in a washing basket full of newspaper /hay that was a lot smaller than the cage they whinged about 
So:
you're boars live apart? Could you get a bigger cage on eBay or Gumtree that you can divide (then sell your indoor one if you want to)
I put a divide in for GP1/GP2 the first winter (but they went to the Pighouse by day so together) they only sleep indoors.
They seemed to 'need' the time to prowl about and play in the hay and all their tunnels.
C&C has the advantage that you can customise the space to fit, but you need a liner (heavy plastic sheeting or lino if they aren;t chewy types). I bought some similar from Costco, and as my pigs don;t like it, I use as shelving but it's good as a temporary cage.
It's the damp more than the cold that affects them, Peru is cold but dry (for all the people who tell you they don;t have Snugglepads in the wild )
And of course there's less daylight .
You can keep guineas outside , lots of people do.
Hay is the best insulator but it needs to be dry hay.And newspaper to absorb. (I put wood based small animal safe cat litter under the paper)
I have two sows who pee rivers so I change the bedding daily. When their inside at night that two bedding changes a day but they only tend to pee in the haybox which makes it easier.