We rent a place for a month every year, randomly found it on craigslist. It's our biggest expense and not at all mustachian, but it also allows us to retain vital relationships. Now that we've been going there year after year we have a good relationship with the owners. They are very flexible with us since they know we are good tenants who respect their property. Having that kind of relationship is awesome.
So add craigslist to your search (along with airbnb + VRBO, we've used them all). Since the market is slowing perhaps you could try talking with with realtors, target specific listings for sale in the area you want to rent and ask if the owners would be interested in renting for the time period you are seeking. Once you get in there as a renter, get the word out and let neighbors/people in the area know exactly what you are looking for. There might be someone interested in renting for this time period who doesn't want to go through the hassle of listing their place. There are a ton of people who rent but never advertise in the area where we rent.
We have toyed with the idea of buying a 2nd home, but the numbers are garbage for us. With that said, if your numbers are good (or even if the numbers aren't great, but the experience is valuable enough), it might be worth it for you.
@Metalcat ended up buying a 2nd place perhaps they could chime in on the experience.
Whatever you do, I hope you update here. I'm interested to know how you solve this.