Is this legit?
 

I needed to respace a hub to 130 so I just added another lock nut (or outer cone or whatever) to either side, I think they are only 4mm but whats a mm here and there right? Are actual axle spacers just thick washers or do they thread on?

Spacers are just washers. The cones and locknuts are the only threaded parts.

That's exactly what I did too. Instead of using spacers I used additional locknuts.
Just make sure they're large enough diameter-wise so they bite into the trackends or dropouts.

yeah, make sure that the nut (weather you use washers or nuts for spacers) with the serrated ridges stays on the outside to grip the frame.

yeah, as long as the bb spindle isn't wider as well and your chainline's fine and your nuts are on the bike correctly (no, dude, the other nuts)...i think it'd be a-okay.

Im running a 103mm spindle and both sets of nuts have the knurled side facing out.
Im thinking that using nuts instead of spacers should actually be stronger since they are threaded on

it wont realy matter either way, just make sure that the nut immediately after the cone is locked down against it. The outermost nut can be loose, since it wont be able to compress/lock the cone through the middle nut.