For stays or fork tubes I would not risk it unless I knew that the frame or fork was a thicker and heavier "cheapie". It's a bit different on the main triangle tubes where you're affecting a lot less of the total percentage of the circumference.

The only other option would be to have the proper mounts brazed onto the legs. The brazed joint and metal of the braze on fitting itself would reinforce the area around the hole needed and make doing it safer.

The other thought is to just get a proper touring fork with the right mounts. If you were to sell off your present fork or use it on another bike then the final "cost" wouldn't be so bad and likely it would be the same or less cost than getting the brazeon fittings added and then repainting the fork.