Motley Crew welcome to irv2 and the Newmar forum.
As Jerry said may have been a option on 05 coach. I have been in both types of heat gas I have and friends Hydro hot. Both work well if the temp is adjusted to compensate for cool spots in coach. The Newmars come with a winter pack option which I have had in all my coachs and we have been as warm as toast.
The gas furnace has a vent powerd by fan to heat holding tank area with this option. The Hydro may just rely on the heat from heating unit in basement compartments or may have a fan asist.
Living in your area would think all coachs would have the winter option.
Enjoy the forums and post often, good luck in your hunt.