Full Audio Upgrade + Cameras / Tips Please

I'm upgrading all audio components on my '06 DoubleCab JBL and adding rear and front parking cameras. I will Self Install as much as I could and see how far I can go. I have checked with Crutchfield about the installation prior to ordering but let me post my plan here in case there are suggestions or things to keep in mind:

1 - The factory amp is behind the rear seat on the driver's side. As all the speaker feeds start there that will be the same place where I place the new amp. I will need to splice the existing factory harness into the one marked with the arrow on the 1st picture so that those wires connect to the factory wires going to the speakers.

2 - To install the new radio, I will connect the "Crux CS-TJ20 Wiring Interface" . I will to splice the wires from the back of the new radio into the harness of the "Crux CS-TJ20 Wiring Interface"

3 - Tweeter installation. I will use the existing bracket and my wife's glue gun to secure them.

4 - I was going to add one camera but parking in New York City sometimes requires use a front camera as well so I'm going with both cameras. I'd like ideas on the best places to mount the front camera (grill, below bumper, etc). I'm feeding the power to both from the radio so that they can be viewed independent of placing the car in "R".

5 - The electrical feeds to both amps needs to come directly from the battery. This is the only item I may need a technician to help me with since I don't want to short-circuit the truck. I may just do as much as I can and then bring it to an installer to finalize the items I couldn't.

All items I'm purchasing from Crutchfield are in the pictures below.

Tips? suggestions? additions?

After this install, I'm taking it to Garden State Undercoating to rust proof the frame.

 

Tip
Watch some YouTube videos. There are a lot of them on the tundra.
5 star car stereo has some good ones.

 

I did this upgrade but went with ALPINE speakers instead of HERTZ hooked up to an ALPINE amplifier instead of the Kenwood. Despite almost 3K in parts and labor, my old Limited Highlander with JBL has fuller sound produces a fuller bass. Is there something in the design or the frame of the Tundra that distorts or hampers the sound?

I'm seriously thinking of having it all taken out and return to factory since there is very little difference.

The installers are certified by ALPINE and have plenty of experience with hundreds of good reviews. Something is off.