I would get somebody out there to look at it. Tell them your plans and let them give you some options. All us armchair quarterbacks can give our .02. But it is best left to those who can take a peek at it. Get recommendations from them regarding HP vs. strip heat. Keep in mind that it will not only run when you are there, but it will also run to maintain whatever temp you set it at to keep pipes from freezing when you are not there. Depending on how cold it gets and your insulation, it might run more than you think.