It took me a bit searching around in my email archives to find this, but JL Audio manufactures what they call sthealth boxes for vehicles that have unused space where a subwoofer may be dropped in. There is a unit for the CR-V which might fit the "E". They may well also create a unit for the "E" itself. One warning - these boxes do not come cheap.
http://www.jlaudio.com/stealthbox/crv.html
Iskie
http://www.jlaudio.com/stealthbox/crv.html
Iskie