I dog sat a malamute over the summer… a very dominant Mal.
Tucker knows this dog, they see each other almost daily, but have had their fair share of nips & growls here & there. We had this dog in our home for a month - and honestly, there were no major issues. I continually made it clear that I AM THE BOSS, neither of the dogs are. I made them BOTH work for everything, as I normally do w/ Tucker. But by doing so, it continually reminded the Mal I'm in charge, not him. Also reminded my own dog, I take care of things, not him.
we fed them in different rooms (since the Mal would take Tucker's face off if he got too close to his food), and we kept them seperated at night, and whenever we couldn't watch them.
I was pleasantly surprised how well it went. I was the boss of the house, but did let my dog keep "his" things to himself. his fav toys, his food, his crates, his blankets, etc.. were all OFF LIMITS to our doggie-guest. basically so Tucker didn't feel "threatened".
when they got things to chew on, they were also seperated. basically I focused on preventing issues before they arose. which seemed to work well.
so yes, take charge, seperate when needed, and prevent issues. have fun dog sitting!