I reviewed the Mar-K finish reports and considered Por-15 but decided to use Smith & Company epoxy sealer follwed by a spar varnish. It is still a work in process given all the coats on all the surfaces but the attached shows the bottom side after the last (I think) coat of varnish.
Our driving season is a little longer than 5 months, maybe 8 dependingon the year, but like you I don't anticipate my truck sitting outside often.
