That Cortina was a MK 1 and it was in an extremely unattractive shade of Ford Shitty Bown that matched the rust spots perfectly. The previous owner had put "Go-faster" stripes down both sides which created the optical illusion that it was speedily rusting before your eyes! The preamp idea is a good one. Again, go to your music store and try it out. Practice repeating the phrase, "Yes, but do you have anything cheaper?" An alternative approach is to check out Audio-Technica's Digital Reference line. I have a DR-G95 acoustic guitar condenser mic, It has a spring clip, mini-gooseneck and mic designed to clamp inside the instrument on to an internal brace of a guitar. You mount it pointing to the rear of the guitar and if you want to get real loud, you can put one of those rubber bungs in the sound hole. The cable hangs out of the soundhole rather like the srting on a a tampon and it is difficult to convert to an end-socket-strap-plug because although it is a 2-wire high-Z from amp to the instrument, it has asmall box containing the batteries and a volume control which goes to a 4-wire cable to the mic. For about $120 it may solve all your problems.