Hi Steve,
In addition to what you have done already you should try the following:
1 - Assuming you are using Chris Hammond template you can open the \BuildScriptsModulePackage.targets file - It is just a regular text file;
2 - Find ".dll" - You will find 2 lines with it;
3 - Right after each on those lines, add the following line:
<Copy SourceFiles="$(MSBuildProjectDirectory)\bin\[YOUR DLL NAME].dll" DestinationFolder="$(MSBuildProjectDirectory)\Package\bin"/>
4 - Replace [YOUR DLL NAME] with the name of your dll;
Note: Make sure you don't have your project open in Visual Studio while you do these changes.
That should do it. It worked well for me.
Check it out and let us know.
Good luck,
Aderson