We find our combi camp lovely and snug! Provided you have electric hookup for a heater if needed!!
For those times when it's not that cold it's still plenty warm enough as we have eliminated the potential draughts.
We have the additional skirt that goes across the side of the trailer/wheel underneath the raised bedroom area.
A large groundsheet is pegged down, overlapping with the bottom flaps on the walls. Over this we use the breathable groundsheet which insulates nicely! We were going to get a carpet but couldn't find the right size and had got the breathable groundsheet for a site where they were stipulated. Both the groundsheet and carpet were bought larger than needed and cut to size and shape.
To prevent draughts coming in under the door area, we use a doormat which we tuck the bottom doorflaps under.
In the sleeping area, we lined the sides with cheap camping mats cut to size and use additional cheap camping mats to insulate underneath the mattress to prevent condensation.
Angela, thank you so much for all your advice. I am going to keep this safe and just as soon as we find a Combi or a Camplet to buy, I will do the same as you. I am really grateful for your experience. Best wishes, Les.