Have a safe trip, Lloyd. The dog and snake thing is something I luckily have not had to consider-one of the regulars here lost an American Water Spaniel, from a breeder local to me, to a Great Basin rattler a few years past. Such would break my heart.
Maybe the only thing worse than the dog being bit, would be you being bit. A kid took a hit in Southeastern Minnesota a few years past from a Timber rattler, was transferred to HCMC, a level 1 trauma center, from a small hospital, and died about three days later. Your chances of being bitten in Minnesota are small, but, small is different than not possible.

Good luck.

Best,
Ted