I did the same with 3D printed hooks. Only problem is they can't move side to side like the newer ones, so linking two two axle trucks with the same old couplers means the wheels don't run true i.e axles not perpendicular to the track. I adapted new hook and loop couplers by chopping off most of the grooved channel (there are holding lines that show where to cut with the Dremel). Then screw on the new couplings with some packing styrene sheet.Later picture, as you can see on the left, there are the two types of LGB hooks, top the current one and below it, the one I have printed. You can see that there is no way of fixing the modern hook to the old style drawbar, as it has a grooved channel.
The way I have fixed the printed hook is to remove the ‘axel’ bar and drill a 3 mm hole in its place, then by careful eye, drill the channel in the drawbar and push a short length of brass tube through to fix it. A drop of super glue secures the rod. There is a ‘pip’ on the print to take a spring to keep the bar up to the loop, I found an old pen spring to be the exact size to do the job ( luckily, I have another to do the 2nd tanker!) .
Despite having reasonably level track, I do find that long trains can come uncoupled and as I don’t generally do any shunting on my railway, the double hooks are more of an advantage than a hindrance .
Dave View attachment 281799