If you think about it, once you get the adjusters set up for a particular wheel/freewheel/derailer/chain combination, you (or at least I) don't fool with them. The same function could be accomplished by getting some aluminum material the thickness of the dropout, and profiled to fit in the slot -- a hacksaw and a file would get the piece in usable shape. Some more trial-and-error fitting with a rat-tail file would get you to the "adjusted" position, and then you could install them semi-permanently with some silicone sealant.