EtN:
I ended up with a second head unit in the glove compartment for now. It's pretty much fixed on one station because it's a hassle to open the glovebox door to change the station. I tried a portable radio (several actually), and the reception Just Sucked. I've looked for remote mounted tuners and only found one.
SecretAudio make a tuner/cd controller that can mount anywhere. the control part is like 1.5x4.5 inches. You could mount this on a stalk, or replace your ashtray with it. But it's more expensive than PCA's tuner at $199usd. (cd changer extra).
I already have a Sony cd changer I want to mount in the glove box, so I'm patiently waiting for PCA's tuner kit.