Man, it sucks that you have to give up riding so early.
I had to look up "berm" to find out that it's Ohio slang for a highway shoulder. The shoulders on US-49, and most larger, divided highways, are pretty sweet. I imagine US-49 is the road you rode on, actually, it's the main thoroughfare through Mississippi and passes right through Arkansas (I actually live half a mile from it). Smaller state highways, unfortunately, don't have those sweet shoulders, even though traffic can get pretty harsh. But in those stretches with shoulders, it's like an entire damn lane of the road all to yourself, they're so wide.
I dunno, there are cold snaps from time to time and it becomes uncomfortable, especially in December. But cold season is, of course, really really short here. I hadn't really taken this into account when I was planning my grandiose tour de America. I really can't expect to set out for anything half that long until midway through October, and even that would kind of be rushing it. But I might run into some uncomfortable cold whether along the way, as I probably won't be back until halfway through November.
Anyway, it is kind of flat, but I suppose you can remedy that by just shifting into a higher gear and riding really hard. Kind of difficult to convince yourself too, though. The big hills force you. I live at the bottom of a creek's drainage basin, nearly at sea level, and there are hills all around climbing back up to the ~250ft above sea level that the rest of the place is at. That's about as hilly as the place gets, honestly. On my ride to Picayune, the hill outside my house was by far the biggest I encountered the entire way. I suppose if I go up and down it about 120 times, cumulatively I will have basically biked up Mount Everest.