Scott,
I found a way to successfully import the solution and the ribbon changes. I tested in Dynamics 365 versions 8.1 and 8.2
I created a new solution and only added the Entity and 1 form (the form I need it) similar like patch solution, no views, and no other items, created the changes on the solution with ribbon workbench and imported (published).
This solution was imported successfully in compare with the solution that had all other forms, views, and all the rest of the entity elements.
Key point is just to have the form and the web resources you will need to the command bar with ribbon workbench.
hope this helps!
Abe Saldana