I have an idea if you want to try it. However, finding a smith to do it is next to impossible. You can try this yourself if you feel you have the ability, or look for someone who is up to the challenge and is also a good gunsmith.
Anyway, this is just an idea. You could add a plastic rail to the dust cover. It could be done in several ways, but personally, I would take some plastic rail stock, trim ut to fit the contours of the frame, drill a few holes in the frame and corresponding ones in the rail stock, and put some supports in the form of plastic dowels or screws. I would build up the gap between the two with Marine-Tex, though you could use Brownells Acra-Glas Gel. It would retexture the whole area after blending, and probably retexture the grip frame while I was at it.
When I was done with all the work, I would dye it and then consider coating it with Dura-Coat. If you lived in Az., I would gladly do it for you, but alas....
The disadvantage to this method is that it's more fragile than steel. However, it's definitely stronger than plastic. Plastic rails seem to work just fine for the hundreds of thousands of Glocks out there. Also, you would not find a holster to fit it, outside of the generic one size fits many nylon holsters. If you're really comitted to this, you could easily make or have made a Kydex holster, or you could send the gun to a custom leather guy.
If you're interested in trying this, let me know. I can give you detailed instructions on how to do this, but it would require that you have a good working knowledge of the 1911, some mechanical aptitude, and a lot of patience. If you want to try a custom smith, I can recommend some that might try it for you.
ETA: I forgot to say that nobody makes a rail that I'm aware of that fits your gun in the U.S. I would look at the Israeli market, as it would not surprise me if there is something made by BUL.