I'm just slightly south of both folks mentioned but I'm about 3000' higher in elevation. My winter temps are much colder and longer.
I'd bet my season is similar to yours, but I can say I have lost a handful of RES for 2 winters here. I found about a dozen last year and 5-6 this winter so far. My RES were sourced out of SC Kansas, straight south of TJ and I'm not aware of any source farther north in KS so if you can find them in NE, I'd try that.
