I only use snugglesafes with rabbits who are ill health or elderly and then bring them indoors.
Rabbits often have cool ears, this is not because they are cold this is because their national body defences reduce the supply of blood to the peripheries when it is cold, thus the ears become cooler than the rest of their body and reduces the amount of heat they loose. This is the same natural response why we have cold ears and hands on a cold day like today.
If a rabbit has cold ears this does not mean they are cold, this only confirms that their natural body defences are working. Giving extra bedding helps to keep them warm.