light tackle

Quite a challenge. I don't see any real problem with a shunt feed but being a purist myself, it's the guywires that are worrisome. a 120' plus...free-standing mast on a wooden platform should work. But that would take some serious anchoring and waxing to keep the wood from water logging. I think any tower company would build you something suitable.

A light tackle approach with nylon guys is what I would do if I insisted on a 'classic quarter-wave.'