I had a tow dolly for a few years.
The problem I always had when lifting the tongue and pushing or pulling is that you could only lift the front (tongue) a little above knee level before the ramps starting hitting and digging in in the rear. This left me in the awkward position of trying to pull or push while bending slightly forward at the waist. For me that was not a comfortable position.
I agree the tongue weighs very little. Moving the contraption would have been a heck of a lot easier and comfortable if I could have lifted the tongue to waist level and then pulled or pushed.
My solution was to sell the dolly and rig for 4-down.