Upgrading the radio: Advice wanted

[RobotMan]

Hi all, I'm new to the forum, and a Yaris owner of 2 weeks now. I've got the hatchback fully loaded, and I'm debating upgrading the sound system.

Before the Yaris I drove a 97 Escort LX (Ford), with a Kenwood head unit, Polk Audio 6.5" Components (which I still have), two Pioneer 10" subwoofers in a sealed box powered by a Bazooka power amp, and a 4ch. amp to run the Components and rear speakers.

Now with the Yaris, I would like to incorporate these into the car, but since this is my first new car and it is significantly smaller than the Escort I drove before, there are a few things holding me back.

First off, I do not want to modify any body panels, interior or exterior. I'd like to keep it looking stock as well, so putting the component speakers in poses a slight problem there.
Second, I would like to have everything hidden, but not in the trunk. Since I went from a trunk that could easily hold all my crap in addition to the 10" subs and both amps to the Yaris trunk, I would like to retain as much (preferably all) of the space in the trunk.
Lastly, if possible I would like to use the Component speakers and amplifiers I already have to save money, and because they are new enough that it is illogical to sell them.

So with that in mind, what would you recommend for upgraded sound in the Yaris? Where or how can I mount the Component speakers to keep a stock look and not modify the body panels? Where are good places to mount the amplifiers without taking up useful space inside the car?