I use the Triss Armor mod, but it's not craftable. In order to make it craftable and improvable, I think I have to do the following, but I wanted to check here in case I'm missing something obvious.

Go into Constructible Objects.
Select RecipeLeather ArmorCuirass. Make a duplicate copy.
Rename the dup to RecipeTrissAmorCuirassUnenchant.
Change the Created Object to TrissArmorCuirassUnenchant.
Maybe change required ingredients.
Save File.
Done.

Am I missing anything? I don't want to just do this and then screw something up.

Any help on this? Is my plan correct, or will it cause problems? Thanks!

I think this would be correct yes.
The armor should show up in the 'misc' section of the smithing menu.

Don't worry about messing up, whatever you do, should be easily fix-able. (As long as you don's mess with scripts)