Well, I for one commend you on your resourcefullness.
I'd probably have done it with some bargain bin fixed size wrenches from the local tool store but if you keep the jaws closed down on the flats there's no reason not to work and work well.
I've never needed two either. I just work the one end by easing off the locknut a 1/8 turn, turn both together to adjust and then snug the locknut back down. So only one thin cone wrench and one locknut standard wrench.