James, I installed that unit in my Plus 2, although may be an earlier generation. I also have a Kenwood amp. Both are mounted in the trunk under the floorboards, right hand side. Speakers are in the stock location on rear parcel shelf (tight clearance) and in the kick panel area (tons of room). If I am out working on the car I can post some pics; need to remove the floor boards to show the install.
I did not install a CD changer, although the unit has the controller built in for this. No need for CD's in such a small car anyways.
I use an older iPod Nano (fourth gen?) with the unit, and it works great. The SST will not work with an iPhone or iPod Touch. I just bought a used compatible Nano that I leave in the car and sync the unit on iTunes, so this is no issue.
The SST has USB, and mine shipped with a thumb drive and a couple of songs loaded to give the idea. Have not used this feature; with the iPod available it is kind of redundant.
I use a Sirius Stiletto for sat radio. The SST unit will not control the Sirius portable tuners, and the firm does not offer the required converter box to do so (like Kenwood, Alpine, etc. do) The Stiletto uses the 3.5 mm audio in jack and works fine. The Sirius antenna is mounted under the fibreglass roof panel at the rear of the car so does not show. Only issue is the wires for the Stiletto car kit are a bit short, so I mounted the holder between my two rear seats. Not a big issue, but requires using the Stiletto remote to change stations, etc. Secretaudio offers a Sirius tuner for this unit, and the SST will control this from the control head or remote. This would work well for your stealth install, but you have to pay an additional monthly subscription for the tuner; couldn't see this working for me with the car laid up half the year.
I fitted the small controller in the stock DIN cutout of my dash. This took a bit of fettling with a thin plastic plate. Why the manufacturer doesn't offer a simple DIN install kit is a bit beyond me. If I knew I was using this unit when I ordered the dash I would have changed the cut-out size for the unit; it is smaller than a DIN size and can be fitted though. The supplied multi-conductor cable is just long enough to reach from the trunk to the dash area. Colour in the controller window is a bright blue; I would have preferred green but it can't be changed.
The RF remote is very good. However, I would not want to try and operate the unit with this alone and not being able to see the info in the controller window. If the newer units have a screen on the remote, this install strategy would probably work well. The remote is so good I thought the unit was pouched as it was randomly changing stations; the wife had placed it in the glove box with stuff on top and buttons were being pressed every bump!
The sound quality of the unit is reasonably clear, but not audiophile quality by any means, at least in the challenged acoustic environment of a Plus 2. The tuner seems to be OK, but radio reception fades quickly outside the city. This may say more about my antenna than the unit itself. The FM tuner can be changed in a menu to Euro tuning standards for anyone on the other side of the pond; not sure of the standards for AM but the details are in the manual pdf. Don't get me wrong, I am very happy with the radio and its stealth install features. I have a constant buzz in my rear speakers, but I think this is electrical interference not a problem with the SST unit.
Here is the manufacturers web site for more info. Somewhere on the site you can download the SST's manual complete with control head dimensions and wiring diagram. This is where I saw the new
Secretaudio SRMS, which has the improved remote that may be more suitable if you hide the control head.
http://www.casmfg.com/Secretaudio.htmHTH
PS Another feature I really like is the radio does not loose all of the station presets when you disconnect the power. This allows disconnecting the car battery for service or storage without screwing up all the settings.
The SRMS model looks like what you are after. It was not on the market when I got my SST.