our FL does not have heated tanks... the heat from furnace duct prevents freezing. We are fulltime and have wintered in CO and PA this past year ...without skirting...no problemo... tho we were concerned about freezing in transit. Left the furnace on during the 3 day drive cross country.
We had tank heaters added by RW. One of those things not on the option list. If you think you want them, do it we you order. It's a lot less expensive than doing it after market.