Yeah, thats definetly a mission impossible
Honestly, if you have alot of drivetrain squeaks/creeks I'd suggest getting under it with some lube and goign wild. Some teflon/silicone spray on the bushings and linkages will do more then you may think. Even if you go to the extent of swapping out all the bushings, you'll end up having
more noise since you'll be running urethane bushings afterwards.
As far as in cabin rattles/etc you just need to track them down and repair/use rubber washers/extra screws etc. to mend them. Chassis noise is one of the more difficult things to pinpoint and eliminate entirely on any car, not to mention a 20+ year old sports car.