my girls sleep on a gel pad which is reasonably cool in hot weather.
in the winter i put sheep skins on top of the gel pad, and place their day bed in front of the woodstove.
in their crate in the car they lie on a 7 cm thick latex mattres which absorbs the worst shocks and jolts from the car. during the summer the mattress is covered with a thick silk sheet (originally bought for myself....) to help regulate the temperature.
in the winter sheep skins go on top of the mattress.
during the nights they sleep in my bed.........