Hi
Options 2 and 3 are ruled out. You can't have 2 costing variants to release standard cost.
In my view, these are the options
1. Option 1 proposed by you
2. Same as option 1. Add an activity type in the same operation rather than a new operation, provided you have not consumed all 6 activities in the work center
3. Costing sheet using overhead key and overhead group. This can be done using same costing variant and order types
4. Use template allocation which is an extension of costing sheets. Recently a document contributed by arturo senosain can be referred. Click on his name and go to the Content tab. You can find ur there
Br. Ajay M