<< I've thought about building a wooden rack that would set on top of the engine cover. >>
Unless you are going to actually fasten this wooden rack down, that's not a good idea. The radio won't stay on the engine hatch in hard turns or stops. If you are going to hard mount it, just bolt the mobile bracket to the top of the hatch. problem is, you have to disconnect everything to remove the hatch to work on the engine.
<<I'm not too keen on having it hang from the headliner "trucker style"..>>
Why not? The radio is up out of the way, it is accessable and all the rest. I have mounted many a commercial control head from the ceiling of vans because that was the most convenient place.
DO NOT hang the mike from the rear view mirror, though. Not only does it look VERY tacky, it stretches the cord quickly.
Lon - W3LK