Accessory power wire question.

So I'd like to wrap up a few items in my car in a few weeks such as finally putting the audio system and the two 12v power ports back in.
Let's say I'd like to make one wire run from inside to under the hood and use that wire to feed a distribution block for both things above...and maybe have a spare spot for something else later. I'm conservative so there WON'T be 4 amplifiers and a 1000w game spotlight, ever. My question is, does this sound like a good idea? Has anyone done this and if so, gimme some details.

Disclaimer:
My thoughts on wiring... Wiring is sized to carry a certain load of the attached items. Fuses are sized so that the wire doesn't burn. (All these numbers are complete rubbish and for example only). So if you have, for example, 10 amps draw from the items and the chart says you need an 8 gauge wire for 20 amps, you have double the wire size, which is fine. The wire won't burn until more than 20 amps are applied, in theory. So if you put an 18 amp fuse in, you are covered. Some people want to mistakenly fuse based on the 10 amps that the equipment draws. That is incorrect. If the wire can safely support 20 amps, why fuse down near 10 amps? Any flaws in my disclaimer?

Been dealing with enormous stress lately so please hold words like idiot, stupid, moron, etc to the bare minimum...lol

Thanks!