New 2026 Outdoors RV Back Country Series MTN TRX 20MKS Travel Trailer

Why We Chose This Back Country Series MTN TRX 20MKS
We selected this specific model because it represents the pinnacle of true off-grid freedom and rugged off-road capability for active couples. Built by Outdoors RV in the Pacific Northwest, the Back Country Series 20MKS is engineered specifically for remote primitive camping, national forests, and unpaved territory. The heart of its off-grid dominance is a built-in Cummins Onan 3.6kW LP generator, allowing you to run your entire electrical system anywhere wild trails take you. The clever floorplan maximizes interior space with a deep slide-out housing a residential sofa with built-in recliners, perfectly positioned across from a 32" swing-out TV. Up front, a space-saving premium queen wall bed flips up effortlessly into the wall to reveal a spacious daytime dining area. Complete with a fully equipped gourmet kitchen with solid-surface countertops, a full rear bathroom, and a 16' power awning, this mountain-ready coach is purpose-built for rugged exploration without sacrificing residential comfort.

Highlights of this Unit:

• Built-In Onan 3.6kW Generator: True boondocking self-sufficiency with an on-board LP generator that powers your entire rig far away from RV parks.

• Custom Off-Road HD Chassis: Built tough with a cambered off-road frame, rugged 16" Goodyear Endurance tires, and an HD fiberglass front cap to withstand backcountry trails.

• Mountain Extreme 4-Season Design: Features advanced thermal pane windows and premium insulation barriers to keep you completely comfortable during freezing winters or scorching summers.
  
  

The Sumner RV Difference
When you partner with Sumner RV, you are joining a 60-year legacy of integrity. As a family-run dealership hand-picked by the Nash family to carry on their tradition, we prioritize long-term customer relationships over transactional sales. To guarantee your absolute peace of mind, we invite new owners to spend their first night right here on our property along our year-round salmon creek—ensuring you are 100% comfortable with every feature before you head out to see Mt. Rainier.