I was thinking of using an inverted V antenna using a wire cored halyard. Over the top of the mast either abeam or length wise.
I want to install some of my ham gear on my boat as well. There a several installation options and what makes me think the most is the termination of the coaxial connection section of the antenna to a point where it will be easy to hook to the back of the radio. The most obvious that comes to mind is to create a termination block on the cabin top above the nav station, with strain relief for the antenna halyard, and cover it when the antenna is disconnected.
I know for your case you might just want to just run the cable through the companionway to the radio and not modify the cabin top.
Just my 1/2 cents worth...