Two things- first, there are amplifiers available (PPI, ADS, among others) that can accept speaker level inputs directly into the RCA inputs. Use the speaker+ as the center pin and ground the shield to the radio chassis. These higher level amps use a very high imput impedence, and are capable of accepting the high voltage input without causing the noise associated with most high/low adapters. There's also a remote pin on the back of the stock deck, so that eliminates the thump instead of usung the ign. lead for remote turn-on. I forgot which one, use a multi-tester to find it. The end result is suprisingly good sound quality (I use the PPI amps, so sound quality had BETTER be good!!).
Second, you can remove your deck without pulling the whole dash. There are two pieces of trim on the sides, they snap in place. Remove them and you'll see the spot for two pairs of Ford/Saab, etc. din-removal tools.