You will be fine with the SR+. Here is my temperature efficiency data from TeslaFi tracking 17,000+ miles on my 3 LR RWD. I've filtered to only drives over 25 miles (I don't have enough data on 50+ mile trips to make that chart useful to you):
As someone else mentioned, distance is a key metric when talking about how range is impacted negatively--if you are taking a ton of 1-mile trips and blasting the heat to warm the car from a cold soak each time, you'll see more impact. If you're charging at home each night and then making your 60-mile trip, then another 60-mile trip home, you will do fine. You can see above that the absolute worst I've gotten is a 30% hit when ambient temp is < 15F. Bump that up to 25F and the worst is a 20% hit. Above freezing and it's at worst a 10% hit.
If you take the 240-mile SR+ range and knock it to 80% (eg you want to keep it between 10% and 90% normally), that's 192 miles rated. Now knock off that worst-case 30% hit: still 134 miles of range. And recall that this is the worst-case scenario, while keeping you between 10 and 90%, and on 25-mile-plus trips. Since you're going 60, your impact would be a bit less than this. More like 150+ under 95% of conditions. You can also set your car to charge so it's finishing up when you leave, resulting in a warm battery and reducing the range impact in cold weather.
Were I in your shoes, I'd absolutely get the SR+. If the weather is particularly terrible, I'd just charge to 95% or 100% that day, or drive a little more slowly., or hit an L2 charger at lunch, or... Lots of options to mitigate. I'd hate to miss out on the best car I've ever driven, 100% of the time, because I was worried about an issue that may surface 5% of the time.
That said, I love my LR RWD--I don't need the extra range 99% of the time, but it's nice to just not ever have to worry about it. If the timing, cost, and availability work out for you to get the LR RWD, it's also a great option.