Those RAM mounts are nice.
You can buy pieces and assemble what is correct for you as well. A little pricey by going that way, but to me, a good lookin' installation is worth a bit more money.
Unfortunately, the boat builders don't think too much about leaving room to add stuff.
Yea, once you drill a few hundred holes, it comes as second nature.
I can see where you want that clamshell cover for the cable. You might also want to consider one of these:
They are cheap, maybe $0.25 each, and are also available from Mouser, and allow you to install the bushing with the cable already installed. I actually have purchased a bunch of these and the other bushings in different sizes for things like running wires through my radar arch.
Look for item E in the page below:
http://www.mouser.com/catalog/632/1636.pdf