I do think it will be pretty cool still... The only reason I wouldn't do it is because I'm not so handy with fiberglass.. but imagine creating a low profile fiberglass inlay that will fit in there? Or maybe even pushing the alcove out, and installing the subs in the space between the ceiling and roof liner, and just having the subs showing through.. that would be very custom.. still daunting, but custom and probably very loud.