We do have it on the list to include "drip" as a part of the pipe data dialog, where you will be able to add blank 17mm tubing and Supply/Exhaust Headers as needed. In the meantime, you are definitely in the right mindset of using a lateral class as the closest thing to 17mm.
The intent of placing emitters in areas was to simply say you can add additional flow without the need of piping to each emitter and the system will pick it up. If you are placing into the area but as a different zone, as long as things are piped, it will be counted on different zones accordingly.
If you have added the equipment as Drip Emitters, and you want to place that type as Drip Emitter Area, you will need to still add that same equipment but under the Area for Drip Emitters, since they are technically different equipment type/function. You could also add multiple Area for Drip emitters and assign the emitters specific to trees vs shrub container sizes and place into the same areas, and have the system only read the selected container size based on equipment.
If you are using the Highlight Station tool and highlighting a zone, it will add the flows of the drip area as well as the flow of the emitters placed (but not piped to) within the area, If this is not the case it might be best that you submit your files in a Tech Support ticket and we can check things out.
I would love to hear others approach to this as well, and definitely let me know if I have misunderstood what you are after and we can get to the bottom of your questions!