Edge M21 vs North Trail 21/22FBS

We like the Edge M21 as it is Light weight. However in my research here, I find it does not have an under belly. Can you tell me the difference between the Edge M21 and the NT 21/22FBS as far as the tanks if they are protected from the cold. I think I read a thread that stated the Edge is not covered and the frame has holes in it for light weight. If we were to travel to the north in the late season then can I assume the north trail would be a better pick? Then my problem is my tow vehicle which I'm trying to get an answer on if it is 5,000 pounds vs 7,000 pounds. That will also make a difference in my choice as I believe the Edge would be NO problem, the NT might be. Hitch max is 500 pounds on my TV.
Thank you Ken

On my edge M18 my tanks are exposed so I assume that the M21 is the same. I have never seen a Northtrail up close so not sure about that one.

You are correct, the Edge is all about light weight and therefore we cut holes in the frame and since there are holes in the frame is doesn't make any since to cover the underbelly on the Edge....However, the NT does have an enclosed and heated underbelly...Hope this helps

North trails have heated and enclosed underbellies and more insulation. There is the Focus line as well, in between the Edge and North Trail as far as equipment, features, and weight. Also heated/enclosed underbelly. GVWR of the Focus FX21 is 5200 pounds, 4100 dry.

What is the tow vehicle? What engine and gearing (axle ratio) if a pickup? Many class 3 hitches have a 500 pound tongue weight limit without a weight distribution system, but higher (800-1200) with WD hitch.