If you're used to turning bolts and have good hand feel, you can get by without a cone wrench. As the crank comes up to position the needed torque will rise steadily. Near final tight the torque will ramp up much faster, as of coming to the wall. After that it's maybe another quarter turn up into the wall (so to speak) and it's quits.

A 6" wrench may not be enough, but an 8-10" is plenty. As I said decent hand feel is needed, but anyone whose tightened stuff long enough can do this.