I hope you decide to check out this section of railroad. It is one of the busiest stretches of railroad in Minnesota, with a wide variety of traffic and some areas that are quite beautiful.
It's not at all difficult to access, but since it is a busy line, there are a lot of railroad employees around. BNSF does not want people trespassing, and for your own safety it's important that you follow this law. There are plenty of very accessible locations where you can photograph trains safely. Stay off the tracks. Stay out of the yards at Staples and in Dilworth. If you choose to violate this advice, expect to be questioned and possibly arrested. Please don't do things that will only make it more difficult for future railfans to enjoy this area.
It gets cold in the winter in this section of Minnesota. I have stood near the Highway 332 overpass at Dilworth in late May and wished I had gloves as I waited to photograph a train. It also can be very hot and humid in the summer. The wind can and usually does blow.
There are a lot of locations to get gas, food, and other essentials such as batteries along the line. You will never be more than 12-15 miles from a gas station or C-store. Lodging is available in Staples, Wadena, Perham, Detroit Lakes, and the Fargo-Moorhead area, so you will never be more than about 20 miles from a hotel.
Highway 10 is a four lane divided highway almost all the way from Staples to Dilworth. People drive FAST on the highway, and traffic can be heavy. If you decide to stop, there are numerous side roads to pull off on. If you must stop along the highway, make sure to get well off the driving lane, and be very careful when you are ready to enter the driving lane again. Oncoming vehicles will be there before you know it. If there is any doubt as to whether you have room to accelerate to speed without blocking traffic, wait for a better opportunity to re-enter the driving lane. If you get injured or killed in a traffic accident your trip will be ruined.
Trains travel fast on the Staples Sub as well. Every year people are killed in grade crossing accidents because they tried to beat the train. I know that this temptation can be especially strong when you are chasing and trying to get to the sunny side of the train for a shot. Don't do it! If the lights are flashing, the gates will be dropping. At the unprotected crossings, make sure you have plenty of time to make it across, or else wait. One good thing is that if you miss a shot, another train will likely be along shortly.
Chasing trains can be a challenge due to their speed. You can usually keep up with them but it can take many miles to overtake a speeding Z train, even when you are stretching the law with your speed. Amtrak trains will likely outrun you no matter what you do. If you decide to chase, be aware that there is a 40 mph speed limit through Verndale and a 30 mph speed limit through Wadena. There are multiple stop lights in Wadena and Detroit Lakes, and a number of communities have speed limits of 50 or 55 mph even if the road appears to be the same high speed highway as out in the country. Examples include Aldrich, Audubon, and Lake Park. Hawley is 40 mph, I think. These speed limits are enforced by local police and I see people pulled over very frequently. If you speed through one of these towns, you will likely get a ticket. Note that the trains do not have the same speed limits (or stop lights) as they pass through towns, which is one of the reasons chasing can be tough. The exception is Staples, where trains all slow as they pass the depot.
Be careful, be polite, and drive safely. Please.