HN's with AQ heater stayed thawed to -12F.@aart - your horizontal nipples do well in the winter, yes? I think, if installed at a slight angle so that any water left in the little drip cup can drain away, they should work without a problem. I also tried them but I just prefer my birds to have a "pool" to drink from rather than the nipples.
Tilting lips could help, hard to do tho and not a deal breaker.