I would go direct to Zifer in Italy to get the right hood. Write to them with your serial number and details because the hood and the way it attaches has changed a lot through the years. The main use for the "winter" hood is for use in the Sahara Desert. You get huge temperature variations where it goes from being very cold at night to super hot. The hood will trap air and give you a bit more warmth in the cold but also reflect the heat in the morning so you can sleep in. It is like putting on a windbreaker. No insulation but will kill the drafts. Attaches with velcro under the lip and drawstring under. You undo the drawstring and stuff it in with the fabric when you fold the tent.
Frenchie has probably spent more time in a Columbus than anyone in the world. He wrote up his notes on what he wanted to improve and they were incorporated into a special "variant" that I liked to call Frenchie's tent. I had one for years and it had some great features , best tent I've owned and would love to have it back. As for his marital advice, it is probably sound but your milage may vary.
The Columbus is a great all around tent, very airy in the summer but can still take a licking in the winter. The Maggiolina is the cold weather champion. I've heard complaints about the Maggiolina being a "coffin" but the critics don't get it. What make is great is that it keeps the warm air down. It was designed like a mountaineering tent. This doesn't mean the Columbus isn't good in cold, it just isn't as good. Folding fabric tents are crap when gets cold. I was with with Frenchie testing an OverCamp tent on his trailer and froze my butt off with two sleeping bags while he was snug in his Extreme.
I set my Columbus up a bit different for cold weather. First thing, most of your heat loss is though the base. First I bulk up my mattress with a condensation mat under and a mattress topper over. Don't use memory foam, I've seen one very experienced cold weather camper use a feather bed topper and he and his wife loved it. The roof is insulated so that is good. The next thing is the "winter" hood, makes it good for four seasons. This will be good to freezing, after that you will have to change from down quilts to a down mummy bag. There is lots of good advice about camping in cold weather here if you search the forum.
