I'm building a log cabin and need to find finishes that are durable and long-lasting, since I live too far away for easy maintenance and I'll be too "cabin poor" to afford frequent maintenance.

I purchased antique heart-pine boards that were salvaged from a tobacco warehouse and remilled as t&g flooring. I spent a little more to get these, partly for character, but mostly because I figure they will be more rot-resistant than other decking options. The porch itself is covered, so probably not much rain exposure except on the edges; morning sun; relatively humid climate (northwest Pennsylvania -- third-cloudiest region in the continental USA).

What is the best way to finish this deck, using what product(s), to give me the most durable finish? Should the boards be prefinished before installing them? All sides or just top, or top and side-edges? Should the finish "breathe" or should the object be to prevent any penetration of moisture or humidity?

I went into this assuming there would be some scientific consensus on what finishes work best for certain objectives, but am quickly realizing that there are many theories and little, if any, independent testing of methods and products.

Thanks for any advice!