We moved into our little house in April of 2016. In December of that same year we not only had 2 additional adults stay for a week, but we also hosted a 2 and 4 year-old. As you may have heard we had one of the warmest Novembers on record. We had visions of campfires on the patio, snowman building, sledding-you know fun outdoor winter activities for the kids. It was warm right up until 2 days before they arrived. The temperatures were in the single digits with below zero wind chills while they were visiting.
The biggest concern was what to do with all the energy that comes with toddlers. 600 square feet on the first floor of the little house does not leave a lot of running room (especially with my Christmas tree up and decorated with the glass ornaments). The frigid temps limited outdoor play.

So does my car really need a roof over it? The answer was no. We cleared out as much space as we could on the first floor of the garage, bought the patio furniture in, and a play area was born! We borrowed a riding car from a friend and invested in a big wheel. We borrowed a train set from friends. My husband filled an empty toolbox with real tools and he turned a refrigerator box into a garage for the riding toys. The toddlers spent hours playing in the garage.
I also cleaned out one of my little storage areas upstairs in our bedroom. It is an area of the house where the roof slants down. I put down a sleeping bag and placed pillows and books in there. The older child was allowed to go up there while the younger one was napping to play quietly, read and/or take a nap. (The child will never admit to falling asleep up there- but it happened)
I moved all of my breakable ornaments to the top of the tree, got out the plastic plates and cups and put away other items that I would have been sad if they had accidently been broken.

I think no matter what size your home is you can host overnight guests even if they bring toddlers! The key is making the space work so they feel welcome and comfortable.