Winter camping means your batts are much lower in capacity just when you have the furnace and lights on most of the day due to cold, short daylight, and you have the highest AH usage.
In summer, you hardly use any AH and the batteries are at full capacity too, so it is all backwards to what you want.
The solution is to get the batteries inside where it is warm from the furnace so the batts have full capacity. Can't do that with Wets usually.
Some chose to have their AGMs inside, thinking that is safe because they don't need venting. In that case, the lower AH per battery of AGMs could be higher than the capacity of a cold Wet Cell.
If course the strict rules say AGMs also need venting, so no go. If you did arrange to have a vented battery compartment in a heated area of the rig, then Wets could go there just as well as AGMs.
That would leave ease of access as the issue for watering and taking hydrometer readings.