DO you have power adjustable driver seat? I'd love to fit the 5 channel RF under there maybe. Under the Bose is another interesting idea...They make good stuff. I have an alpine pdr-v75 amp and it works well: 4x100 line outs and a 350 watt out for the sub. It's under the driver seat.
The OEM Bose amp was cut out of its spot and flipped over to make more space. It feeds into the Rockford Fosgate LOC which feeds the Alpine amp which then feeds the hi-lo splitters that came with my Focal speakers (hi's go to the tweeters and lo's to the door speakers). This is all fit under the passenger seat. (Except the Alpine amp). The 350 watt line out for the amp goes under the flooring and seats from the amp directly to my hatch to power the sub. The thinline sub doesn't take much space and didn't require a stealth install. I still have a spare tire and the ability to load up stuff in back.
Good luck with your project.