What GPS for a Roadster/Convertable

I've been using a TomTom GO720 in my MGB roadster. With the top down and the sun out, the display is completely washed out and un-viewable. Also with the top down, the little speaker is completely inaudible at highway speed.

I've gotten around the sound problem by patching the headphone output on the TomTom to the Aux input on my radio. With this arrangement, I can make the sound loud enough to overcome the road noise. This doesn't solve the screen wash-out problem, but I can clearly hear the voice directions.

I would like to buy a new GPS (mostly for the lifetime map updates), but none of the new models has a headphone output. Any suggestions? Surely, I'm not the only person in the world who wants to use GPS in a convertible.

Bobby Dipole