My policy has always been one lens one camera and having 6 Nikons makes this easy when on a commercial job. Now I am selling up and reducing to 2 bodies so lens changing will have to happen. I hate camera bags so that's not going to happen so how do you do it ...take lens off camera ..find lens cap in bag ..fit select new lens remove lens cap fit to camera .now some of this takes three hands etc …
So the solution is to mount two F mounts back to back and suspend them from your belt or whatever . I used two extension tubes and fitted the mounts back to back with a black plastic separator .
So now you have lens no2 hanging from your belt ..you take lens 1 off the camera and fit it into the empty F mount. Then remove lens 2 and fit it to the camera.
If you insist on a camera bag then glue two lens caps back to back and just swop the lenses end for end .