@dman530. The only parts that I bought were the Ram mounts. There was enough cable length to allow me to splice into the accessory power (the one that looks like a cigarette lighter) behind the helm. The fuse for the helm accessory power is 20 amps, and I think that the in-line fuse that came with the chartplotter was only something like 3 amps, so I figured that it would be safe to splice.
I bought a bunch of Ram mount bits but settled on using these ones for the install:
6" arm: RAM-B-201U-C
Mount for chartplotter: RAM-B-202-G2U
Mount for boat: RAM-B-202U
If I were to do it again, I'd consider using a larger ball size. My Ram mounts have 1" balls. I find that after a some big waves on the way to/from Bimin, the chartplotter settles (moves about a half inch). Although it doesn't impact functionality, it's not a good thing if you're OCD. Maybe a larger ball size would prevent this.