Remotes dont work when too cold..
Did he take pump totally off or just leave remote?
If took pump off.. Good for him.. Considering he went low.. I would say if he did take pump off today. Do again tomorrow but lower basals for two hours before he goes if poss... This wld keep him up a bit more whilst sledging.
If just case of leaving remote behind.. I again would lower basal before he goes out including the whole time he is out...
Does that make sense?
Make sure he has hypo stoppers with him!