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here is my take on this for its worth. It is hard to have one tandem to do it all however I am just completing a Calfee adventure tandem. We commissioned an Adventure tetra with S&S couplers that would fit your bill quite nicely. It is designed around a 700c wheel geometry and utilizes a Whisky Cyclocross fork with thru axle. The frame geometry was modified to allow the different AC dimension to ride like a road bike. The rear triangle was designed to allow a large tire (the fork has lots of clearance). In this end I built a set of carbon 27.5 wheels using WTB Horizon 47mm tires that fit perfectly and match the diameter of 700c wheels and tires. This bike can use our Zipp 404 fast wheels , Velocity Aileron wheels, or the 650b large tire wheels without any modifications. I am building it as a drop bar DI2 XTR triple with hydraulic 785 brakes. Utilizing Middleburg modular cranks I can/could change to a double setup if we did a combo/supported unsupported trip so we could hang with our fast friends on the road by gearing it up. Our intended use is touring and gravel road touring and some simple single track. I don't think a carbon bike is any less durable and is certainly very repairable. We went with raw carbon no paint so it won't get paint scratches. Craig Calfee told me once that he could easily make us a travel repair kit that we could use to keep us riding in most situations if we had damage on an isolated trip. This bike is as close to a one quiver bike as I could figure out. It would probably work in trails like Moab but not really the best choice. We already have a tricked out Calfee tetra road and Ventana full suspension and Ventana fat tire tandems for use in the more extreme conditions. For what you are describing you probably don't need a full suspension tandem. I have a serious bike habit and a very enabling Stoker(wife) that loves to ride hence all the bikes. I'll post pictures soon but we have 3 ft of snow in the front yard so first ride is a ways off.