I have some exposure to this as an owner of a Chinese electric bicycle.
To get that speed and range you will need
lots of battery capacity- big and heavy and moderately expensive (lead acid), or less big and heavy but even more expensive (li-ion or whatever high-tech); pick your poison. You will be on the upper end for voltage too in order to get your desired speed. Cali is hilly and you will need plenty of gear choices for the pedalling part.
My electric bike looks pretty much like a C70, and it has a great rack!
The biggest thing I don't like about my electric bike is that the pedalling part of it seems to be just a legal formality- it can be pedalled but it ain't no fun. I'd say you don't want the ergos set up so that you're sitting on it like a C70- you want it set up like a bicycle first and foremost if you are serious about helping it along via pedalling. Now if that means traditional upright or recumbent or whatever, that is up to you but I know scooter ergos are all wrong for pedalling.
My latest and greatest electric bicycle dream revolves around a full-suspension aluminum mountain bike with an electric hub motor, stout battery pack, and large basket(s)/rack(s). Oh- and fenders too (raining today and I got the ol' stripe
).