Definitely go with a latex stain made for log homes. Perma Chink’s Ultra 2 is my brand of choice. Not sure what you mean by ”guard strip”, but if you mean ”Grip Strip” foam do not go cheap. It MUST be a closed cell foam used behind the chink/caulk. If you try to use the bead board or blue board it will give off formaldehyde gas and cause the chink/caulk to bubble.