speedster on 4/27/2012 4:51:22 PM:
Yes, more rolling resistance for sure with 2 extra wheels. As you mentioned, one wheel will likely always be on the 'bad line' with the dandelions and overgrowth. Average speeds should be factored in as slower than a conventional set-up without trailer, as there's no way in hell you'll make anything close to 12-15mph average going this route.
I prefer to just use panniers along with a backpack if need be, if your gear carrying needs are significant.
From my perspective, a trailer always seems like a good idea in theory, but when you get out there and actually put 'wheel to trail', it never works out as well as imagined.