Hi fortified and Tiny
My boys do indoors/outdoors but when they are out they have a wooden Playhouse (now The Pighouse) which was originally for my DC.
I was going to put a hutch in the Pighouse but we thought "Why not let them have the entire floor as their area?"
The Pighouse is on a solid wooden base which is raised but secured round the edges (no foxes can get under but it doesn't sit on the earth so though our garden flooded, the Pighouse was safe)
If they are in a hutch , they do need protected against draught and damp- it depends where you are in the country as to your temperatures. IIRC this week our overnight temp will get down to 2c.
You can get the covers (they are ££) or try old carpet and thick tarpaulin over the top and front (but allow ventilation)
We have a heater (oil filled radiator) in the house , on top of the haybox lid to keep it away from sharp teeth.
Lots of hay to insulate them.
The temp they are comfortable at? I've read loads of different views.
I try to keep mine between 12-18 in their Pighouse (they don't have draughts to contend with, and they have always got hay. I put Snugglepads in too if I think it's chilly). (They've got a thermometer
)
I find the high summer temperatures are more of a challenge. It's difficult to keep them cool but still protected.
In winter they are indoors at night in the small bedroom ( it's not heated but there's no door so it's slightly cooler than house temp to keep them comfy)
When I look inside their Pighouse they are active and grubbing around. Their haynests are cosy. Their ears and feet warm.
So if you wanted to keep them outside , it can be done with enough shelter - lots of people do.