Bismarck, ND, here. And I've got several great twenty mile routes- rolling hills, beautiful scenery. Only problem with the out and back routes- the wind! Write when you come back this way.
I lived in Fargo for several years and did a lot of running. It should be about the perfect time of year to get good weather conditions. Fargo is very flat but it also can get very windy. I would check out the Lake Agassiz Pacers website. I haven't lived there since 1992 only thing that really bothered me as far as running goes was the smell from the Crystal sugar plant which probably isn't that harmful to your health. Overall the air quality was very good compared to other places I have run. Good luck
There is a FM Tri Club. If you search Facebook for the FM Tri Club, you'll find it. The Facebook page is very active with people discussing tri-related issues.