this is not a good idea. i have seen it when people run a welded front with one hub unlocked. it might be ok on completely dry surfaces, but on any kind of slick or uneven traction, it tends to have funny characteristic.
there are several axles that can be converted to rear locking hubs. the reason that people mainly do this to jeeps, it because they like to flat tow them, say behind their motorhome. that way they dont burnup the t-case even though it is in neutral.
though this may have an advantage like you think, there are other dis-advantages. one of them being the "play" that you would be introducing to the drive train. locking hubs have a sort of "wind-up". ever notice the front tires of a rig in 4 wheel drive, and the power to them has sort of a pulse? this is partly due to all the play in the entire drivetrain. some of this cant be avoided such as the play in drivelines. but some can. this is one of the reasons people put flanges in the front axle. they are stronger and have less play because of less moving parts.
one more thing to remember, hubs can only go on a full float axle.
