Hi Greeneyes,
The reason you are getting a sudden downwards bump when you forget to take your meds is because levodopa has a very short half life in the body, unlike most medication that taper down slowly. The best way to deal with this is make sure you take it on time. Do talk to your neuro about this, and also ask him/her whether it is possible to take a lower dose at shorter intervals. There is a half size sinemet tablet 62.5. This might give a smoother delivery. Dividing doses has been helpful for some parkinson patients.

The other thing you can do is always have some meds on you so you can take some when your body reminds you that you need it. Just remember not to take more than you are prescribed. If you don't want to use a pill dispenser, other options are a wrist watch with alarms settings, or maybe an app for your mobie to remind you.

There is a treatment called duodopa that consists of a device that drip feeds levodopa in a gel form into the gut. It is currently a very expensive treatment and used for people in later stages of parkinson, and I haven't heard of it being used for DRD. As it is quite an intrusive device it usually isn't given till all other options have been explored.

Good luck and keep us posted on how you are getting on.