Once you get the first trip done, you'll feel much more comfortable as you learn what to expect. I just completed my first long road trip in my AWD GTL and found that mentally using 200 miles as the car's range works great for curing range anxiety. If you assume the car's range is 200 miles, then each one percent of battery is 2 miles. You can look on the trip info screen and see if you're above 2 miles for each battery SOC percentage. If your mileage on the trip so far is higher than double 100 minus the current battery SOC, then you are on a pace to exceed 200 miles. Since your trip length is 200 miles, this should work perfectly for you.
My trip was through New York's 1000-2000 foot mountains, entirely at speeds of 65-75 (mostly 75). I was always exceeding 2 miles per 1% SOC, so I was always exceeding 200 mile range.
Every trip has the potential for being different, due to temperature, road conditions, and wind. In most permutations, you'll probably make 200 miles, but there may be circumstances where you won't, such as very cold temperatures, with a headwind in both directions. It's good to have a backup plan in case you're running low on charge, which can be as simple as slowing down or taking a break someplace with a level 2 charger. Most of the time you should be fine. Needless to say, you want to start the trip at 100%.
Use SCC. If possible, follow a large truck or other vehicle while using SCC that is going about the same speed as you are. It will punch a nice hole in the air for you. SCC does a good job of driving smoothly and keeps a safe distance from the vehicle ahead.