What you have listed above is basically all correct. What you mostly like would want to do instead the Replace Thing ID which will break is source your camel to your game system. Then simply turn off Bestiary and you will see only one camel.
Another idea, a little more advance, is to keep a .user file that is only on YOUR computer and never given to your players (ie Hidden.user). This would simply be used to do a
*PRECLUDE ( a tab in the editor) of the Camel from the Bestiary on your computer only when you have your Game Source Turned on.
This way your players only see the Custom Camel as they have no Bestiary. You only see the Custom Camel when you turn on your Game Source. This way if you wanted to see the Real Bestiary or UE Things you would just turn off your game source and BOOM all official items get shown.
When you turn on your Game source only the Custom version of Things will be displayed. As you never give your players this "Hidden.user" file their stuff will just load up the custom creations only.
Example:
All my house rules run under "Shadow d20" (source.srcShdwd20)
1) So I make a new version of the Camel(thingid.rS2Camel)
2) in my Hidden.user file on the *PRECLUDE tab I have it set so when Shadow d20 is ON the official Camel is hidden.
-- srcShdwd20 rCamel
3) Do not distribute Hidden.user to your players. They only ever see rS2Camel and now you only ever see rS2Camel as long as "Shadow d20" source is active.
Note: Interchange names above with your own stuff.
No replace thing needed. Hope that helps.