I suppose it all depends on your area, but my 65lb dog is far bigger than a coyote here. Plus coyotes are skittish little doggos who are scared off easily. Not like wolves in coordinated packs. You’re likely looking to deter them, not fight them.I was told that Pyrenees can physically stand up to coyotes due to their size and thick fur and skin. Also, goat breeders in my area swear by them. Yes my current dog is an inside dog. He does like to be outside as much as possible, and has 'asked' to sleep in the goat pen at night, but he is not cold tolerant and gets shivers quickly. But you raise a good question, maybe a second dog is not necessary.
I would suggest a line of electric fencing - even a mobile one - in lieu of a new dog until you have a lot of time for training. You will have a marvelous LGD one day, but more animals that need training can really = more problems if the solution is a quick one (electric rope fence).
Also, when it gets warmer your current dog can sleep in the barn and get his scent all over it and this may do a bit of deterrence in its own.
That’s just my 2 cents but I don’t know your exact situation.