My new farmer's porch has a 1x4 mahogany board floor (not tongue and groove), and I would like to know how best to finish it. Some say Z Spar varnish, some say just an oil protectant. If I do the oil, can I ever go to the varnish or paint later? How should I prep the surface (is dirty now from the construction crew). What will wear best (traffic will be light). Thanks.